<PAGE>   1

     As filed with the Securities and Exchange Commission on August 25, 1999

                                                   Registration No. 333-________
================================================================================

                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                              --------------------

                                    FORM S-8

                             REGISTRATION STATEMENT
                                      Under
                           The Securities Act of 1933

                              --------------------


                               ACT NETWORKS, INC.
--------------------------------------------------------------------------------
             (Exact name of registrant as specified in its charter)


          DELAWARE                                               77-0152144
---------------------------------                            -------------------
  (State or other jurisdiction                                 (IRS Employer
of incorporation or organization)                            Identification No.)


                             26707 WEST AGOURA ROAD
                           CALABASAS, CALIFORNIA 91302
                                 (818) 871-6400
--------------------------------------------------------------------------------
               (Address of principal executive offices) (Zip Code)

                              --------------------

                            1997 STOCK INCENTIVE PLAN
           1997 NON-EXECUTIVE OFFICER STOCK OPTION/STOCK ISSUANCE PLAN
                           OPTION GRANTED TO MR. URIBE
--------------------------------------------------------------------------------
                            (Full title of the Plans)

                              --------------------

                                 SUSAN N. CAYLEY
                               V.P., LEGAL AFFAIRS
                               ACT NETWORKS, INC.
                             26707 WEST AGOURA ROAD
                           CALABASAS, CALIFORNIA 91302
                                 (818) 871-6400
--------------------------------------------------------------------------------
                     (Name and address of agent for service)


                         CALCULATION OF REGISTRATION FEE

<TABLE>
<CAPTION>
===============================================================================================================================
                                                                          Offering
                                                      Amount to be          Price           Aggregate             Amount of
Title of Securities to be Registered                  Registered(1)       per share       Offering Price       Registration Fee
-------------------------------------------------------------------------------------------------------------------------------
<S>                                                   <C>                 <C>             <C>                  <C>
1997 Stock Incentive Plan                            200,000 shares         $10.56         $2,112,000.00          $  587.14(2)
Common Stock, $0.001 par value
-------------------------------------------------------------------------------------------------------------------------------
1997 Non-Executive Officer Stock                     250,000 shares         $10.56         $2,640,000.00          $  733.92(2)
Option/Stock Issuance Plan
Common Stock, $0.001 par value
-------------------------------------------------------------------------------------------------------------------------------
Option Granted to Mr. Uribe                          150,000 shares         $11.1250       $1,668,750.00          $  463.91(3)
Common Stock, $0.001 par value
-------------------------------------------------------------------------------------------------------------------------------
Aggregate Registration Fee                                                                                        $1,784.97
===============================================================================================================================
</TABLE>

(1)   This Registration Statement shall also cover any additional shares of
      Common Stock which become issuable under the 1997 Stock Incentive Plan,
      1997 Non-Executive Officer Stock Option/Stock Issuance Plan and Option
      granted to Mr. Uribe by reason of any stock dividend, stock split,
      recapitalization or other similar transaction effected without the
      Registrant's receipt of consideration which results in an increase in the
      number of the outstanding shares of Registrant's Common Stock.

(2)   Calculated solely for purposes of this offering under Rule 457(h) of the
      Securities Act of 1933, as amended, on the basis of the average of the
      high and low selling prices per share of Registrant's Common Stock on
      August 20, 1999, as reported by the Nasdaq National Market.

(3)   Calculated solely for purposes of this offering under Rule 457(h) of the
      Securities Act of 1933, as amended, on the basis of the exercise price of
      the option granted to the listed individual.

================================================================================
<PAGE>   2

                                     PART II

               INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

Item 3. Incorporation of Documents by Reference

        ACT Networks, Inc. (the "Registrant") hereby incorporates by reference
into this Registration Statement the following documents previously filed with
the Securities and Exchange Commission (the "Commission"):


        (a) The Registrant's Annual Report on Forms 10-K and 10-K/A for the
            fiscal year ended June 30, 1998, filed with the Commission on
            September 28, 1998 and October 14, 1998, respectively;

        (b) The Registrant's Quarterly Reports on Form 10-Q for the fiscal
            quarters ended September 30, 1998, December 31, 1998 and March 31,
            1999 filed with the Commission on November 16, 1998;, February 12,
            1999 and May 17, 1999, respectively; and


        (c) The Registrant's Registration Statement No. 000-25740 on Forms 8-A
            and 8-A/A, filed with the Commission on March 23, 1995 and April 25,
            1995, respectively, in which the terms, rights and provisions
            applicable to the Registrant's Common Stock are described.


        All reports and definitive proxy or information statements filed
pursuant to Section 13(a), 13(c), 14 or 15(d) of the Securities and Exchange Act
of 1934, as amended (the "1934 Act") after the date of this Registration
Statement and prior to the filing of a post-effective amendment which indicates
that all securities offered hereby have been sold or which deregisters all
securities then remaining unsold shall be deemed to be incorporated by reference
into this Registration Statement and to be a part hereof from the date of filing
of such documents. Any statement contained in a document incorporated or deemed
to be incorporated by reference herein shall be deemed to be modified or
superseded for purposes of this Registration Statement to the extent that a
statement contained herein or in any subsequently filed document which also is
deemed to be incorporated by reference herein modifies or supersedes such
statement. Any such statement so modified or superseded shall not be deemed,
except as so modified or superseded, to constitute a part of this Registration
Statement.

Item 4. Description of Securities

        Not Applicable.

Item 5. Interests of Named Experts and Counsel

        Not Applicable.


                                      II-1

<PAGE>   3

Item 6. Indemnification of Directors and Officers


        Under Section 145 of the Delaware General Corporation Law, the
Registrant has broad powers to indemnify its directors and officers against
liabilities they may incur in such capacities, including liabilities under the
Securities Act of 1933, as amended (the "1933 Act"). The Registrant's Bylaws
(the "Bylaws") provide that the Registrant shall indemnify its directors and
officers to the extent any such officer or director acted (i) in good faith,
(ii) in a manner reasonably believed to be in or not opposed to the best
interests of the Registrant, and (iii) with respect to any criminal action or
proceeding, with reasonable cause to believe such conduct was lawful. The
Registrant believes that indemnification under its Bylaws covers at least
negligence and gross negligence and requires the Registrant to advance
litigation expenses in the case of stockholder derivative actions or other
actions, against an undertaking by the director or officer to repay such
advances if it is ultimately determined that such individual is not entitled to
indemnification. The Bylaws further provide that rights conferred under such
Bylaws shall not be deemed to be exclusive of any other right such person may
have or acquire under any agreement, vote of stockholders or disinterested
directors, or otherwise.

        In addition, the Registrant's Certificate of Incorporation (the
"Certificate of Incorporation") provides that, pursuant to Delaware law, no
director shall be liable for monetary damages for breach of his or her fiduciary
duty of care to the Registrant and its stockholders. This provision in the
Certificate of Incorporation does not eliminate the duty of care, and in
appropriate circumstances, equitable remedies such as injunctive or other forms
of non-monetary relief will remain available under Delaware law. In addition,
each director will continue to be subject to liability for breach of the
director's duty of loyalty to the Registrant for acts or omissions not in good
faith or involving intentional misconduct, for knowing violations of law, for
actions leading to improper personal benefit to the director, and for payment of
dividends or approval of stock repurchases or redemptions that are unlawful
under Delaware law. The provision also does not affect a director's
responsibilities under any other law, such as the federal securities laws or
state or federal environmental laws. The Certificate of Incorporation further
provides that the Registrant shall indemnify its directors and officers to the
fullest extent permitted by law and requires the Registrant to advance
litigation expenses in the case of stockholder derivative actions or other
actions, against an undertaking by the director to repay such advances if it is
ultimately determined that the director is not entitled to indemnification. The
Certificate of Incorporation also provides that rights conferred under such
Certificate of Incorporation shall not be deemed to be exclusive of any other
right such person may have or acquire under any statute, the Certificate of
Incorporation, the Bylaws or any agreement, vote of stockholders or
disinterested directors, or otherwise.

        The Registrant has obtained a liability insurance policy for its
officers and directors that, subject to certain limitations, terms and
conditions, will insure them against losses arising from wrongful acts (as
defined by the policy) in their capacity as directors or officers.

        In addition, the Registrant has entered into agreements to indemnify its
directors and certain of its officers in addition to the indemnification
provided for in the Certificate of Incorporation and Bylaws. These agreements,
among other things, indemnify the Registrant's directors and certain of its
officers for certain expenses (including attorneys fees), judgments, fines and
settlement amounts incurred by such person in any action or proceeding,
including any action by or in the right of the Registrant, on account of
services as a director or officer of the Registrant or as a director or officer
of any subsidiary of the Registrant, or as a director or officer of any other
company or enterprise that the person provides services to at the request of the
Registrant.

Item 7. Exemption from Registration Claimed

        Not Applicable.


                                      II-2

<PAGE>   4

Item 8. Exhibits

Number            Exhibit
------            -------

   4        Instruments Defining the Rights of Stockholders. Reference is made
            to the Registrant's Registration Statement No. 000-25740 on Form
            8-A, and the amendment thereto, including the exhibits thereto,
            which are incorporated herein by reference pursuant to Item 3(c) of
            this Registration Statement.

   5        Opinion and consent of Brobeck, Phleger & Harrison LLP.

  23.1      Consent of Ernst & Young LLP, Independent Accountants.

  23.2      Consent of Brobeck, Phleger & Harrison LLP is contained in Exhibit
            5.

  24        Power of Attorney. Reference is made to page II-5 of this
            Registration Statement.

  99.1      1997 Stock Incentive Plan (as amended November 6, 1998).

  99.2*     Form of Notice of Grant of Stock Option - Installment Option.

  99.3*     Form of Stock Option Agreement - Installment Option.

  99.4*     Form of Notice of Grant of Stock Option - Immediately Exercisable
            Option.

  99.5*     Form of Stock Option Agreement - Immediately Exercisable Option.

  99.6*     Form of Addendum to Stock Option Agreement (Limited Stock
            Appreciation Rights).

  99.7*     Form of Addendum to Stock Option Agreement (Involuntary Termination
            following Change in control).

  99.8*     Form of Stock Purchase Agreement.

  99.9*     Form of Addendum to Stock Purchase Agreement (Involuntary
            Termination Following Change in Control).

  99.10*    Form of Automatic Notice of Initial Grant.

  99.11*    Form of Automatic Notice of Annual Grant.

  99.12*    Form of Automatic Stock Option Agreement.

  99.13     1997 Non-Executive Officer Stock Option/Stock Issuance Plan (as
            amended January 18, 1999).

  99.14**   Form of Notice of Grant of Stock Option to be generally used in
            connection with the 1997 Non-Executive Officer Stock Option/Stock
            Issuance Plan.

  99.15**   Form of Stock Option Agreement to be generally used in connection
            with the Discretionary Option Grant Program of the 1997
            Non-Executive Officer Stock Option/Stock Issuance Plan.

  99.16**   Form of Addendum to Stock Option Agreement (Involuntary Termination
            Following Change in Control).

  99.17     Form of Notice of Grant of Stock Option used in connection with the
            Option granted to Mr. Uribe.

  99.18     Form of Stock Option Agreement used in connection with the Option
            granted to Mr. Uribe.

---------------

  *   Exhibits 99.2 through 99.12 are incorporated herein by reference to
      Exhibits 99.2 through 99.12, respectively, to Registrant's Registration
      Statement on Form S-8, Registration No. 333-44087, filed with the
      Commission on January 12, 1998.

  **  Exhibits 99.14 through 99.16 are incorporated herein by reference to
      Exhibits 10.29 through 10.31, respectively, to Registrant's Quarterly
      Report on Form 10-Q for the fiscal quarter ended March 31, 1997, filed
      with the Commission on May 15, 1997.


                                      II-3


<PAGE>   5
Item 9. Undertakings

        A. The undersigned Registrant hereby undertakes: (1) to file, during any
period in which offers or sales are being made, a post-effective amendment to
this Registration Statement (i) to include any prospectus required by Section
10(a)(3) of the 1933 Act, (ii) to reflect in the prospectus any facts or events
arising after the effective date of this Registration Statement (or the most
recent post-effective amendment thereof) which, individually or in the
aggregate, represent a fundamental change in the information set forth in this
Registration Statement and (iii) to include any material information with
respect to the plan of distribution not previously disclosed in this
Registration Statement or any material change to such information in this
Registration Statement; provided, however, that clauses (1)(i) and (1)(ii) shall
not apply if the information required to be included in a post-effective
amendment by those paragraphs is contained in periodic reports filed by the
Registrant pursuant to Section 13 or Section 15(d) of the 1934 Act that are
incorporated by reference into this Registration Statement; (2) that for the
purpose of determining any liability under the 1933 Act each such post-effective
amendment shall be deemed to be a new registration statement relating to the
securities offered therein and the offering of such securities at that time
shall be deemed to be the initial bona fide offering thereof; and (3) to remove
from registration by means of a post-effective amendment any of the securities
being registered which remain unsold at the termination of the Registrant's 1997
Stock Incentive Plan or 1997 Non-Executive Officer Stock Option/Stock Issuance
Plan or the Option granted to Mr. Uribe.

        B. The undersigned Registrant hereby undertakes that, for purposes of
determining any liability under the 1933 Act, each filing of the Registrant's
annual report pursuant to Section 13(a) or Section 15(d) of the 1934 Act that is
incorporated by reference into this Registration Statement shall be deemed to be
a new registration statement relating to the securities offered therein, and the
offering of such securities at that time shall be deemed to be the initial bona
fide offering thereof.

        C. Insofar as indemnification for liabilities arising under the 1933 Act
may be permitted to directors, officers or controlling persons of the Registrant
pursuant to the indemnification provisions summarized in Item 6 or otherwise,
the Registrant has been advised that, in the opinion of the Commission, such
indemnification is against public policy as expressed in the 1933 Act, and is,
therefore, unenforceable. In the event that a claim for indemnification against
such liabilities (other than the payment by the Registrant of expenses incurred
or paid by a director, officer or controlling person of the Registrant in the
successful defense of any action, suit, or proceeding) is asserted by such
director, officer or controlling person in connection with the securities being
registered, the Registrant will, unless in the opinion of its counsel the matter
has been settled by controlling precedent, submit to a court of appropriate
jurisdiction the question whether such indemnification by it is against public
policy as expressed in the 1933 Act and will be governed by the final
adjudication of such issue.



                                      II-4

<PAGE>   6
                                   SIGNATURES

        Pursuant to the requirements of the Securities Act of 1933, as amended,
the Registrant certifies that it has reasonable grounds to believe that it meets
all of the requirements for filing on Form S-8, and has duly caused this
Registration Statement to be signed on its behalf by the undersigned, thereunto
duly authorized, in the City of Calabasas, State of California on this 25th day
of August, 1999.

                                       ACT NETWORKS, INC.


                                       By: /s/ Andre de Fusco
                                           -------------------------------------
                                           Andre de Fusco
                                           President and Chief Executive Officer

                                POWER OF ATTORNEY

KNOW ALL PERSONS BY THESE PRESENTS:

        That the undersigned officers and directors of ACT Networks, Inc., a
Delaware corporation, do hereby constitute and appoint Andre de Fusco and Martin
Woll and each of them, the lawful attorneys-in-fact and agents with full power
and authority to do any and all acts and things and to execute any and all
instruments which said attorneys and agents, and any one of them, determine may
be necessary or advisable or required to enable said corporation to comply with
the Securities Act of 1933, as amended, and any rules or regulations or
requirements of the Securities and Exchange Commission in connection with this
Registration Statement. Without limiting the generality of the foregoing power
and authority, the powers granted include the power and authority to sign the
names of the undersigned officers and directors in the capacities indicated
below to this Registration Statement, to any and all amendments, both
pre-effective and post-effective, and supplements to this Registration
Statement, and to any and all instruments or documents filed as part of or in
conjunction with this Registration Statement or amendments or supplements
thereof, and each of the undersigned hereby ratifies and confirms that all said
attorneys and agents, or any one of them, shall do or cause to be done by virtue
hereof. This Power of Attorney may be signed in several counterparts.

        IN WITNESS WHEREOF, each of the undersigned has executed this Power of
Attorney as of the date indicated.

        Pursuant to the requirements of the Securities Act of 1933, as amended,
this Registration Statement has been signed below by the following persons in
the capacities and on the dates indicated.

<TABLE>
<CAPTION>

Signature                                            Title                                  Date
---------                                            -----                                  ----
<S>                                          <C>                                         <C>
/s/ Andre de Fusco                           President, Chief Executive                  August 25, 1999
------------------------------------         Officer and Director
Andre de Fusco                               (Principal Executive Officer)


/s/ Martin Woll                              Vice President, Finance and                 August 25, 1999
------------------------------------         Chief Financial Officer
Martin Woll                                  (Principal Financial Officer)


/s/ Robert J. Faulk                          Controller                                  August 25, 1999
------------------------------------         (Principal Accounting Officer)
Robert J. Faulk


/s/ William Ambrose                          Director                                    August 25, 1999
------------------------------------
William Ambrose


/s/ Harold R. Johnson                        Director                                    August 25, 1999
------------------------------------
Harold R. Johnson


/s/ Archie J. McGill                         Director                                    August 25, 1999
------------------------------------
Archie J. McGill


/s/ Frederick W. Gluck                       Director                                    August 25, 1999
------------------------------------
Frederick W. Gluck
</TABLE>

                                      II-5
<PAGE>   7

                       SECURITIES AND EXCHANGE COMMISSION

                                WASHINGTON, D.C.



                                    EXHIBITS

                                       TO

                                    FORM S-8

                                      UNDER

                             SECURITIES ACT OF 1933


                               ACT NETWORKS, INC.



<PAGE>   8

                                 EXHIBIT INDEX

Number                             Exhibit
------                             -------

   4        Instruments Defining the Rights of Stockholders. Reference is made
            to the Registrant's Registration Statement No. 000-25740 on Form
            8-A, and the amendment thereto, including the exhibits thereto,
            which are incorporated herein by reference pursuant to Item 3(c) of
            this Registration Statement.

   5        Opinion and consent of Brobeck, Phleger & Harrison LLP.

  23.1      Consent of Ernst & Young LLP, Independent Accountants.

  23.2      Consent of Brobeck, Phleger & Harrison LLP is contained in Exhibit
            5.

  24        Power of Attorney. Reference is made to page II-5 of this
            Registration Statement.

  99.1      1997 Stock Incentive Plan (as amended November 6, 1998).

  99.2*     Form of Notice of Grant of Stock Option - Installment Option.

  99.3*     Form of Stock Option Agreement - Installment Option.

  99.4*     Form of Notice of Grant of Stock Option - Immediately Exercisable
            Option.

  99.5*     Form of Stock Option Agreement - Immediately Exercisable Option.

  99.6*     Form of Addendum to Stock Option Agreement (Limited Stock
            Appreciation Rights).

  99.7*     Form of Addendum to Stock Option Agreement (Involuntary Termination
            following Change in control).

  99.8*     Form of Stock Purchase Agreement.

  99.9*     Form of Addendum to Stock Purchase Agreement (Involuntary
            Termination Following Change in Control).

  99.10*    Form of Automatic Notice of Initial Grant.

  99.11*    Form of Automatic Notice of Annual Grant.

  99.12*    Form of Automatic Stock Option Agreement.

  99.13     1997 Non-Executive Officer Stock Option/Stock Issuance Plan (as
            amended January 18, 1999).

  99.14**   Form of Notice of Grant of Stock Option to be generally used in
            connection with the 1997 Non-Executive Officer Stock Option/Stock
            Issuance Plan.

  99.15**   Form of Stock Option Agreement to be generally used in connection
            with the Discretionary Option Grant Program of the 1997
            Non-Executive Officer Stock Option/Stock Issuance Plan.

  99.16**   Form of Addendum to Stock Option Agreement (Involuntary Termination
            Following Change in Control).

  99.17     Form of Notice of Grant of Stock Option used in connection with the
            Option granted to Mr. Uribe.

  99.18     Form of Stock Option Agreement used in connection with the Option
            granted to Mr. Uribe.

---------------

  *   Exhibits 99.2 through 99.12 are incorporated herein by reference to
      Exhibits 99.2 through 99.12, respectively, to Registrant's Registration
      Statement on Form S-8, Registration No. 333-44087, filed with the
      Commission on January 12, 1998.

  **  Exhibits 99.14 through 99.16 are incorporated herein by reference to
      Exhibits 10.29 through 10.31, respectively, to Registrant's Quarterly
      Report on Form 10-Q for the fiscal quarter ended March 31, 1997, filed
      with the Commission on May 15, 1997.
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1

     As filed with the Securities and Exchange Commission on August 25, 1999

                                                   Registration No. 333-________
================================================================================

                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                              --------------------

                                    FORM S-8

                             REGISTRATION STATEMENT
                                      Under
                           The Securities Act of 1933

                              --------------------

                               ACT NETWORKS, INC.
--------------------------------------------------------------------------------
             (Exact name of registrant as specified in its charter)

          DELAWARE                                               77-0152144
---------------------------------                            -------------------
  (State or other jurisdiction                                 (IRS Employer
of incorporation or organization)                            Identification No.)

                             26707 WEST AGOURA ROAD
                           CALABASAS, CALIFORNIA 91302
                                 (818) 871-6400
--------------------------------------------------------------------------------
               (Address of principal executive offices) (Zip Code)

                              --------------------

                            1997 STOCK INCENTIVE PLAN
           1997 NON-EXECUTIVE OFFICER STOCK OPTION/STOCK ISSUANCE PLAN
                           OPTION GRANTED TO MR. URIBE
--------------------------------------------------------------------------------
                            (Full title of the Plans)

                              --------------------

                                 SUSAN N. CAYLEY
                               V.P., LEGAL AFFAIRS
                               ACT NETWORKS, INC.
                             26707 WEST AGOURA ROAD
                           CALABASAS, CALIFORNIA 91302
                                 (818) 871-6400
--------------------------------------------------------------------------------
                     (Name and address of agent for service)

                         CALCULATION OF REGISTRATION FEE
===============================================================================================================================
                                                                          Offering
                                                      Amount to be          Price           Aggregate             Amount of
Title of Securities to be Registered                  Registered(1)       per share       Offering Price       Registration Fee
-------------------------------------------------------------------------------------------------------------------------------
1997 Stock Incentive Plan                            200,000 shares         $10.56         $2,112,000.00          $  587.14(2)
Common Stock, $0.001 par value
-------------------------------------------------------------------------------------------------------------------------------
1997 Non-Executive Officer Stock                     250,000 shares         $10.56         $2,640,000.00          $  733.92(2)
Option/Stock Issuance Plan
Common Stock, $0.001 par value
-------------------------------------------------------------------------------------------------------------------------------
Option Granted to Mr. Uribe                          150,000 shares         $11.1250       $1,668,750.00          $  463.91(3)
Common Stock, $0.001 par value
-------------------------------------------------------------------------------------------------------------------------------
Aggregate Registration Fee                                                                                        $1,784.97
===============================================================================================================================
(1)   This Registration Statement shall also cover any additional shares of
      Common Stock which become issuable under the 1997 Stock Incentive Plan,
      1997 Non-Executive Officer Stock Option/Stock Issuance Plan and Option
      granted to Mr. Uribe by reason of any stock dividend, stock split,
      recapitalization or other similar transaction effected without the
      Registrant's receipt of consideration which results in an increase in the
      number of the outstanding shares of Registrant's Common Stock.

(2)   Calculated solely for purposes of this offering under Rule 457(h) of the
      Securities Act of 1933, as amended, on the basis of the average of the
      high and low selling prices per share of Registrant's Common Stock on
      August 20, 1999, as reported by the Nasdaq National Market.

(3)   Calculated solely for purposes of this offering under Rule 457(h) of the
      Securities Act of 1933, as amended, on the basis of the exercise price of
      the option granted to the listed individual.

================================================================================
2

                                     PART II

               INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

Item 3. Incorporation of Documents by Reference

        ACT Networks, Inc. (the "Registrant") hereby incorporates by reference
into this Registration Statement the following documents previously filed with
the Securities and Exchange Commission (the "Commission"):

        (a) The Registrant's Annual Report on Forms 10-K and 10-K/A for the
            fiscal year ended June 30, 1998, filed with the Commission on
            September 28, 1998 and October 14, 1998, respectively;

        (b) The Registrant's Quarterly Reports on Form 10-Q for the fiscal
            quarters ended September 30, 1998, December 31, 1998 and March 31,
            1999 filed with the Commission on November 16, 1998;, February 12,
            1999 and May 17, 1999, respectively; and

        (c) The Registrant's Registration Statement No. 000-25740 on Forms 8-A
            and 8-A/A, filed with the Commission on March 23, 1995 and April 25,
            1995, respectively, in which the terms, rights and provisions
            applicable to the Registrant's Common Stock are described.

        All reports and definitive proxy or information statements filed
pursuant to Section 13(a), 13(c), 14 or 15(d) of the Securities and Exchange Act
of 1934, as amended (the "1934 Act") after the date of this Registration
Statement and prior to the filing of a post-effective amendment which indicates
that all securities offered hereby have been sold or which deregisters all
securities then remaining unsold shall be deemed to be incorporated by reference
into this Registration Statement and to be a part hereof from the date of filing
of such documents. Any statement contained in a document incorporated or deemed
to be incorporated by reference herein shall be deemed to be modified or
superseded for purposes of this Registration Statement to the extent that a
statement contained herein or in any subsequently filed document which also is
deemed to be incorporated by reference herein modifies or supersedes such
statement. Any such statement so modified or superseded shall not be deemed,
except as so modified or superseded, to constitute a part of this Registration
Statement.

Item 4. Description of Securities

        Not Applicable.

Item 5. Interests of Named Experts and Counsel

        Not Applicable.

                                      II-1
3

Item 6. Indemnification of Directors and Officers

        Under Section 145 of the Delaware General Corporation Law, the
Registrant has broad powers to indemnify its directors and officers against
liabilities they may incur in such capacities, including liabilities under the
Securities Act of 1933, as amended (the "1933 Act"). The Registrant's Bylaws
(the "Bylaws") provide that the Registrant shall indemnify its directors and
officers to the extent any such officer or director acted (i) in good faith,
(ii) in a manner reasonably believed to be in or not opposed to the best
interests of the Registrant, and (iii) with respect to any criminal action or
proceeding, with reasonable cause to believe such conduct was lawful. The
Registrant believes that indemnification under its Bylaws covers at least
negligence and gross negligence and requires the Registrant to advance
litigation expenses in the case of stockholder derivative actions or other
actions, against an undertaking by the director or officer to repay such
advances if it is ultimately determined that such individual is not entitled to
indemnification. The Bylaws further provide that rights conferred under such
Bylaws shall not be deemed to be exclusive of any other right such person may
have or acquire under any agreement, vote of stockholders or disinterested
directors, or otherwise.

        In addition, the Registrant's Certificate of Incorporation (the
"Certificate of Incorporation") provides that, pursuant to Delaware law, no
director shall be liable for monetary damages for breach of his or her fiduciary
duty of care to the Registrant and its stockholders. This provision in the
Certificate of Incorporation does not eliminate the duty of care, and in
appropriate circumstances, equitable remedies such as injunctive or other forms
of non-monetary relief will remain available under Delaware law. In addition,
each director will continue to be subject to liability for breach of the
director's duty of loyalty to the Registrant for acts or omissions not in good
faith or involving intentional misconduct, for knowing violations of law, for
actions leading to improper personal benefit to the director, and for payment of
dividends or approval of stock repurchases or redemptions that are unlawful
under Delaware law. The provision also does not affect a director's
responsibilities under any other law, such as the federal securities laws or
state or federal environmental laws. The Certificate of Incorporation further
provides that the Registrant shall indemnify its directors and officers to the
fullest extent permitted by law and requires the Registrant to advance
litigation expenses in the case of stockholder derivative actions or other
actions, against an undertaking by the director to repay such advances if it is
ultimately determined that the director is not entitled to indemnification. The
Certificate of Incorporation also provides that rights conferred under such
Certificate of Incorporation shall not be deemed to be exclusive of any other
right such person may have or acquire under any statute, the Certificate of
Incorporation, the Bylaws or any agreement, vote of stockholders or
disinterested directors, or otherwise.

        The Registrant has obtained a liability insurance policy for its
officers and directors that, subject to certain limitations, terms and
conditions, will insure them against losses arising from wrongful acts (as
defined by the policy) in their capacity as directors or officers.

        In addition, the Registrant has entered into agreements to indemnify its
directors and certain of its officers in addition to the indemnification
provided for in the Certificate of Incorporation and Bylaws. These agreements,
among other things, indemnify the Registrant's directors and certain of its
officers for certain expenses (including attorneys fees), judgments, fines and
settlement amounts incurred by such person in any action or proceeding,
including any action by or in the right of the Registrant, on account of
services as a director or officer of the Registrant or as a director or officer
of any subsidiary of the Registrant, or as a director or officer of any other
company or enterprise that the person provides services to at the request of the
Registrant.

Item 7. Exemption from Registration Claimed

        Not Applicable.

                                      II-2
4

Item 8. Exhibits

Number            Exhibit
------            -------

   4        Instruments Defining the Rights of Stockholders. Reference is made
            to the Registrant's Registration Statement No. 000-25740 on Form
            8-A, and the amendment thereto, including the exhibits thereto,
            which are incorporated herein by reference pursuant to Item 3(c) of
            this Registration Statement.

   5        Opinion and consent of Brobeck, Phleger & Harrison LLP.

  23.1      Consent of Ernst & Young LLP, Independent Accountants.

  23.2      Consent of Brobeck, Phleger & Harrison LLP is contained in Exhibit
            5.

  24        Power of Attorney. Reference is made to page II-5 of this
            Registration Statement.

  99.1      1997 Stock Incentive Plan (as amended November 6, 1998).

  99.2*     Form of Notice of Grant of Stock Option - Installment Option.

  99.3*     Form of Stock Option Agreement - Installment Option.

  99.4*     Form of Notice of Grant of Stock Option - Immediately Exercisable
            Option.

  99.5*     Form of Stock Option Agreement - Immediately Exercisable Option.

  99.6*     Form of Addendum to Stock Option Agreement (Limited Stock
            Appreciation Rights).

  99.7*     Form of Addendum to Stock Option Agreement (Involuntary Termination
            following Change in control).

  99.8*     Form of Stock Purchase Agreement.

  99.9*     Form of Addendum to Stock Purchase Agreement (Involuntary
            Termination Following Change in Control).

  99.10*    Form of Automatic Notice of Initial Grant.

  99.11*    Form of Automatic Notice of Annual Grant.

  99.12*    Form of Automatic Stock Option Agreement.

  99.13     1997 Non-Executive Officer Stock Option/Stock Issuance Plan (as
            amended January 18, 1999).

  99.14**   Form of Notice of Grant of Stock Option to be generally used in
            connection with the 1997 Non-Executive Officer Stock Option/Stock
            Issuance Plan.

  99.15**   Form of Stock Option Agreement to be generally used in connection
            with the Discretionary Option Grant Program of the 1997
            Non-Executive Officer Stock Option/Stock Issuance Plan.

  99.16**   Form of Addendum to Stock Option Agreement (Involuntary Termination
            Following Change in Control).

  99.17     Form of Notice of Grant of Stock Option used in connection with the
            Option granted to Mr. Uribe.

  99.18     Form of Stock Option Agreement used in connection with the Option
            granted to Mr. Uribe.

---------------

  *   Exhibits 99.2 through 99.12 are incorporated herein by reference to
      Exhibits 99.2 through 99.12, respectively, to Registrant's Registration
      Statement on Form S-8, Registration No. 333-44087, filed with the
      Commission on January 12, 1998.

  **  Exhibits 99.14 through 99.16 are incorporated herein by reference to
      Exhibits 10.29 through 10.31, respectively, to Registrant's Quarterly
      Report on Form 10-Q for the fiscal quarter ended March 31, 1997, filed
      with the Commission on May 15, 1997.

                                      II-3
5
Item 9. Undertakings

        A. The undersigned Registrant hereby undertakes: (1) to file, during any
period in which offers or sales are being made, a post-effective amendment to
this Registration Statement (i) to include any prospectus required by Section
10(a)(3) of the 1933 Act, (ii) to reflect in the prospectus any facts or events
arising after the effective date of this Registration Statement (or the most
recent post-effective amendment thereof) which, individually or in the
aggregate, represent a fundamental change in the information set forth in this
Registration Statement and (iii) to include any material information with
respect to the plan of distribution not previously disclosed in this
Registration Statement or any material change to such information in this
Registration Statement; provided, however, that clauses (1)(i) and (1)(ii) shall
not apply if the information required to be included in a post-effective
amendment by those paragraphs is contained in periodic reports filed by the
Registrant pursuant to Section 13 or Section 15(d) of the 1934 Act that are
incorporated by reference into this Registration Statement; (2) that for the
purpose of determining any liability under the 1933 Act each such post-effective
amendment shall be deemed to be a new registration statement relating to the
securities offered therein and the offering of such securities at that time
shall be deemed to be the initial bona fide offering thereof; and (3) to remove
from registration by means of a post-effective amendment any of the securities
being registered which remain unsold at the termination of the Registrant's 1997
Stock Incentive Plan or 1997 Non-Executive Officer Stock Option/Stock Issuance
Plan or the Option granted to Mr. Uribe.

        B. The undersigned Registrant hereby undertakes that, for purposes of
determining any liability under the 1933 Act, each filing of the Registrant's
annual report pursuant to Section 13(a) or Section 15(d) of the 1934 Act that is
incorporated by reference into this Registration Statement shall be deemed to be
a new registration statement relating to the securities offered therein, and the
offering of such securities at that time shall be deemed to be the initial bona
fide offering thereof.

        C. Insofar as indemnification for liabilities arising under the 1933 Act
may be permitted to directors, officers or controlling persons of the Registrant
pursuant to the indemnification provisions summarized in Item 6 or otherwise,
the Registrant has been advised that, in the opinion of the Commission, such
indemnification is against public policy as expressed in the 1933 Act, and is,
therefore, unenforceable. In the event that a claim for indemnification against
such liabilities (other than the payment by the Registrant of expenses incurred
or paid by a director, officer or controlling person of the Registrant in the
successful defense of any action, suit, or proceeding) is asserted by such
director, officer or controlling person in connection with the securities being
registered, the Registrant will, unless in the opinion of its counsel the matter
has been settled by controlling precedent, submit to a court of appropriate
jurisdiction the question whether such indemnification by it is against public
policy as expressed in the 1933 Act and will be governed by the final
adjudication of such issue.

                                      II-4
6
                                   SIGNATURES

        Pursuant to the requirements of the Securities Act of 1933, as amended,
the Registrant certifies that it has reasonable grounds to believe that it meets
all of the requirements for filing on Form S-8, and has duly caused this
Registration Statement to be signed on its behalf by the undersigned, thereunto
duly authorized, in the City of Calabasas, State of California on this 25th day
of August, 1999.

                                       ACT NETWORKS, INC.

                                       By: /s/ Andre de Fusco
                                           -------------------------------------
                                           Andre de Fusco
                                           President and Chief Executive Officer

                                POWER OF ATTORNEY

KNOW ALL PERSONS BY THESE PRESENTS:

        That the undersigned officers and directors of ACT Networks, Inc., a
Delaware corporation, do hereby constitute and appoint Andre de Fusco and Martin
Woll and each of them, the lawful attorneys-in-fact and agents with full power
and authority to do any and all acts and things and to execute any and all
instruments which said attorneys and agents, and any one of them, determine may
be necessary or advisable or required to enable said corporation to comply with
the Securities Act of 1933, as amended, and any rules or regulations or
requirements of the Securities and Exchange Commission in connection with this
Registration Statement. Without limiting the generality of the foregoing power
and authority, the powers granted include the power and authority to sign the
names of the undersigned officers and directors in the capacities indicated
below to this Registration Statement, to any and all amendments, both
pre-effective and post-effective, and supplements to this Registration
Statement, and to any and all instruments or documents filed as part of or in
conjunction with this Registration Statement or amendments or supplements
thereof, and each of the undersigned hereby ratifies and confirms that all said
attorneys and agents, or any one of them, shall do or cause to be done by virtue
hereof. This Power of Attorney may be signed in several counterparts.

        IN WITNESS WHEREOF, each of the undersigned has executed this Power of
Attorney as of the date indicated.

        Pursuant to the requirements of the Securities Act of 1933, as amended,
this Registration Statement has been signed below by the following persons in
the capacities and on the dates indicated.
Signature                                            Title                                  Date
---------                                            -----                                  ----
/s/ Andre de Fusco                           President, Chief Executive                  August 25, 1999
------------------------------------         Officer and Director
Andre de Fusco                               (Principal Executive Officer)

/s/ Martin Woll                              Vice President, Finance and                 August 25, 1999
------------------------------------         Chief Financial Officer
Martin Woll                                  (Principal Financial Officer)

/s/ Robert J. Faulk                          Controller                                  August 25, 1999
------------------------------------         (Principal Accounting Officer)
Robert J. Faulk

/s/ William Ambrose                          Director                                    August 25, 1999
------------------------------------
William Ambrose

/s/ Harold R. Johnson                        Director                                    August 25, 1999
------------------------------------
Harold R. Johnson

/s/ Archie J. McGill                         Director                                    August 25, 1999
------------------------------------
Archie J. McGill

/s/ Frederick W. Gluck                       Director                                    August 25, 1999
------------------------------------
Frederick W. Gluck
II-5
7

                       SECURITIES AND EXCHANGE COMMISSION

                                WASHINGTON, D.C.

                                    EXHIBITS

                                       TO

                                    FORM S-8

                                      UNDER

                             SECURITIES ACT OF 1933

                               ACT NETWORKS, INC.
8

                                 EXHIBIT INDEX

Number                             Exhibit
------                             -------

   4        Instruments Defining the Rights of Stockholders. Reference is made
            to the Registrant's Registration Statement No. 000-25740 on Form
            8-A, and the amendment thereto, including the exhibits thereto,
            which are incorporated herein by reference pursuant to Item 3(c) of
            this Registration Statement.

   5        Opinion and consent of Brobeck, Phleger & Harrison LLP.

  23.1      Consent of Ernst & Young LLP, Independent Accountants.

  23.2      Consent of Brobeck, Phleger & Harrison LLP is contained in Exhibit
            5.

  24        Power of Attorney. Reference is made to page II-5 of this
            Registration Statement.

  99.1      1997 Stock Incentive Plan (as amended November 6, 1998).

  99.2*     Form of Notice of Grant of Stock Option - Installment Option.

  99.3*     Form of Stock Option Agreement - Installment Option.

  99.4*     Form of Notice of Grant of Stock Option - Immediately Exercisable
            Option.

  99.5*     Form of Stock Option Agreement - Immediately Exercisable Option.

  99.6*     Form of Addendum to Stock Option Agreement (Limited Stock
            Appreciation Rights).

  99.7*     Form of Addendum to Stock Option Agreement (Involuntary Termination
            following Change in control).

  99.8*     Form of Stock Purchase Agreement.

  99.9*     Form of Addendum to Stock Purchase Agreement (Involuntary
            Termination Following Change in Control).

  99.10*    Form of Automatic Notice of Initial Grant.

  99.11*    Form of Automatic Notice of Annual Grant.

  99.12*    Form of Automatic Stock Option Agreement.

  99.13     1997 Non-Executive Officer Stock Option/Stock Issuance Plan (as
            amended January 18, 1999).

  99.14**   Form of Notice of Grant of Stock Option to be generally used in
            connection with the 1997 Non-Executive Officer Stock Option/Stock
            Issuance Plan.

  99.15**   Form of Stock Option Agreement to be generally used in connection
            with the Discretionary Option Grant Program of the 1997
            Non-Executive Officer Stock Option/Stock Issuance Plan.

  99.16**   Form of Addendum to Stock Option Agreement (Involuntary Termination
            Following Change in Control).

  99.17     Form of Notice of Grant of Stock Option used in connection with the
            Option granted to Mr. Uribe.

  99.18     Form of Stock Option Agreement used in connection with the Option
            granted to Mr. Uribe.

---------------

  *   Exhibits 99.2 through 99.12 are incorporated herein by reference to
      Exhibits 99.2 through 99.12, respectively, to Registrant's Registration
      Statement on Form S-8, Registration No. 333-44087, filed with the
      Commission on January 12, 1998.

  **  Exhibits 99.14 through 99.16 are incorporated herein by reference to
      Exhibits 10.29 through 10.31, respectively, to Registrant's Quarterly
      Report on Form 10-Q for the fiscal quarter ended March 31, 1997, filed
      with the Commission on May 15, 1997.