<PAGE>   1

     As filed with the Securities and Exchange Commission on May 26, 2000
                                                          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 Identification No.)
of incorporation or organization)

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

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

                            1997 STOCK INCENTIVE PLAN
                           OPTION GRANTED TO MR. SADR
                          OPTION GRANTED TO MR. WEISMAN

                            (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>

 Title of Securities to be Registered     Amount to be      Offering       Aggregate         Amount of
                                         Registered(1)        Price     Offering Price     Registration
                                                            per Share                           Fee
=========================================================================================================
<S>                                      <C>              <C>         <C>                  <C>

1997 Stock Incentive Plan                200,000 shares       $11.25       $2,250,000      $   594.00 (2)
Common Stock, $0.001 par value

Option Granted to Mr. Sadr               200,000 shares       $8.625       $2,000,000      $   455.40 (3)
Common Stock, $0.001 par value

Option Granted to Mr. Weisman             90,000 shares       $10.00       $  900,000      $   237.60 (3)
Common Stock, $0.001 par value
                                                           Aggregate Registration Fee      $ 1,287.00
=========================================================================================================
</TABLE>

(1) This Registration Statement shall also cover any additional shares of Common
    Stock which become issuable under the 1997 Stock Incentive Plan and Option
    granted to Mr. Sadr and Option granted to Mr. Weisman 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 May 22,
    2000, 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 for the fiscal
               year ended June 30, 1999, filed with the Commission on September
               28, 1999;

               (b) The Registrant's Quarterly Reports on Form 10-Q for the
               fiscal quarters ended September 30, 1999, December 31, 1999,
               March 31, 2000 filed with the Commission on November 12, 1999,
               February 14, 2000, May 15, 2000, respectively;

               (c) The Registrant's Current Report on Form 8-K filed with the
               Commission on May 3, 2000; and

               (d) 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, as
        amended, including the exhibits thereto, which is incorporated herein by
        reference pursuant to Item 3(c) of this 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 October 21, 1999).
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   Notice of Grant of Stock Option used in connection with the Options
        granted to Mr. Sadr.
99.14   Notice of Grant of Stock Option used in connection with the Options
        granted to Mr. Weisman.
99.15   Form of Stock Option Agreement used in connection with the Options
        granted to Messrs. Sadr and Weisman.
99.16   Form of Written Compensation Agreement for Messrs. Sadr and Weisman.
99.17   Form of Addendum to Stock Option Agreement (Involuntary Termination
        following Change in control) for Messrs. Sadr and Weisman.

               * 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.


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 the Option granted to Mr. Sadr or the Option granted to
Mr. Weisman.


               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


                                      II-3
<PAGE>   5

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 May, 2000.

                                      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 Robert Faulk 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 Officer     May 25, 2000
--------------------------------         and Director
    Andre de Fusco                       (Principal Executive Officer)


/s/ ROBERT J. FAULK                      Vice President, Finance and            May 25, 2000
-------------------------------          Chief Financial Officer
    Robert J. Faulk                      (Principal Financial Officer)
</TABLE>


                                      II-5

<PAGE>   7

<TABLE>
<CAPTION>

Signature                                   Title                               Date
---------                                   -----                               ----

<S>                                         <C>                                 <C>
/s/ WILLIAM W. FREDERICK                    Corporate Controller                May 25, 2000
--------------------------------            (Principal Accounting Officer)
    William W. Frederick



/s/ WILLIAM AMBROSE                         Director                            May 25, 2000
--------------------------------
    William Ambrose



/s/ ROBERT MUSSELWHITE                      Director                            May 25, 2000
--------------------------------
    Robert Musslewhite



/s/ ARCHIE J. MCGILL                        Director                            May 25, 2000
--------------------------------
    Archie J. McGill


/s/ FREDERICK W. GLUCK                      Director                            May 25, 2000
--------------------------------
    Frederick W. Gluck
</TABLE>



<PAGE>   8

                       SECURITIES AND EXCHANGE COMMISSION

                                WASHINGTON, D.C.



                                    EXHIBITS

                                       TO

                                    FORM S-8

                                      UNDER

                             SECURITIES ACT OF 1933


                               ACT NETWORKS, INC.

                                  EXHIBIT INDEX



Exhibit        Exhibit
-------        -------
4       Instruments Defining the Rights of Stockholders. Reference is made to
        the Registrant's Registration Statement No. 000-25740 on Form 8-A, as
        amended, including the exhibits thereto, which is incorporated herein by
        reference pursuant to Item 3(c) of this 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 October 21, 1999).
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   Notice of Grant of Stock Option used in connection with the Options
        granted to Mr. Sadr.
99.14   Notice of Grant of Stock Option used in connection with the Options
        granted to Mr. Weisman.
99.15   Form of Stock Option Agreement used in connection with the Options
        granted to Messrs. Sadr and Weisman.
99.16   Form of Written Compensation Agreement for Messrs. Sadr and Weisman.
99.17   Form of Addendum to Stock Option Agreement (Involuntary Termination
        following Change in control) for Messrs. Sadr and Weisman.

               * 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.
[{"type": "S-8", "sequence": "1", "description": "FORM S-8", "secsgml_size_bytes": 24819}]
{"company-data": {"conformed-name": "ACT NETWORKS INC", "cik": "0000942132", "assigned-sic": "3576", "irs-number": "770396887", "state-of-incorporation": "DE", "fiscal-year-end": "0630"}, "filing-values": {"form-type": "S-8", "act": "33", "file-number": "333-37908", "film-number": "644176"}, "business-address": {"street1": "188 CAMINO RD", "city": "CAMARILLO", "state": "CA", "zip": "93012", "phone": "8053882474"}, "mail-address": {"street1": "188 CAMINO RUIZ", "city": "CAMARILLO", "state": "CA", "zip": "93012"}}
1

     As filed with the Securities and Exchange Commission on May 26, 2000
                                                          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 Identification No.)
of incorporation or organization)

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

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

                            1997 STOCK INCENTIVE PLAN
                           OPTION GRANTED TO MR. SADR
                          OPTION GRANTED TO MR. WEISMAN

                            (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
Title of Securities to be Registered     Amount to be      Offering       Aggregate         Amount of
                                         Registered(1)        Price     Offering Price     Registration
                                                            per Share                           Fee
=========================================================================================================
1997 Stock Incentive Plan                200,000 shares       $11.25       $2,250,000      $   594.00 (2)
Common Stock, $0.001 par value

Option Granted to Mr. Sadr               200,000 shares       $8.625       $2,000,000      $   455.40 (3)
Common Stock, $0.001 par value

Option Granted to Mr. Weisman             90,000 shares       $10.00       $  900,000      $   237.60 (3)
Common Stock, $0.001 par value
                                                           Aggregate Registration Fee      $ 1,287.00
=========================================================================================================
(1) This Registration Statement shall also cover any additional shares of Common
    Stock which become issuable under the 1997 Stock Incentive Plan and Option
    granted to Mr. Sadr and Option granted to Mr. Weisman 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 May 22,
    2000, 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 for the fiscal
               year ended June 30, 1999, filed with the Commission on September
               28, 1999;

               (b) The Registrant's Quarterly Reports on Form 10-Q for the
               fiscal quarters ended September 30, 1999, December 31, 1999,
               March 31, 2000 filed with the Commission on November 12, 1999,
               February 14, 2000, May 15, 2000, respectively;

               (c) The Registrant's Current Report on Form 8-K filed with the
               Commission on May 3, 2000; and

               (d) 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, as
        amended, including the exhibits thereto, which is incorporated herein by
        reference pursuant to Item 3(c) of this 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 October 21, 1999).
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   Notice of Grant of Stock Option used in connection with the Options
        granted to Mr. Sadr.
99.14   Notice of Grant of Stock Option used in connection with the Options
        granted to Mr. Weisman.
99.15   Form of Stock Option Agreement used in connection with the Options
        granted to Messrs. Sadr and Weisman.
99.16   Form of Written Compensation Agreement for Messrs. Sadr and Weisman.
99.17   Form of Addendum to Stock Option Agreement (Involuntary Termination
        following Change in control) for Messrs. Sadr and Weisman.

               * 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.

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 the Option granted to Mr. Sadr or the Option granted to
Mr. Weisman.

               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

                                      II-3
5

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 May, 2000.

                                      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 Robert Faulk 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 Officer     May 25, 2000
--------------------------------         and Director
    Andre de Fusco                       (Principal Executive Officer)

/s/ ROBERT J. FAULK                      Vice President, Finance and            May 25, 2000
-------------------------------          Chief Financial Officer
    Robert J. Faulk                      (Principal Financial Officer)
II-5
7
Signature                                   Title                               Date
---------                                   -----                               ----
/s/ WILLIAM W. FREDERICK                    Corporate Controller                May 25, 2000
--------------------------------            (Principal Accounting Officer)
    William W. Frederick

/s/ WILLIAM AMBROSE                         Director                            May 25, 2000
--------------------------------
    William Ambrose

/s/ ROBERT MUSSELWHITE                      Director                            May 25, 2000
--------------------------------
    Robert Musslewhite

/s/ ARCHIE J. MCGILL                        Director                            May 25, 2000
--------------------------------
    Archie J. McGill

/s/ FREDERICK W. GLUCK                      Director                            May 25, 2000
--------------------------------
    Frederick W. Gluck
8

                       SECURITIES AND EXCHANGE COMMISSION

                                WASHINGTON, D.C.

                                    EXHIBITS

                                       TO

                                    FORM S-8

                                      UNDER

                             SECURITIES ACT OF 1933

                               ACT NETWORKS, INC.

                                  EXHIBIT INDEX

Exhibit        Exhibit
-------        -------
4       Instruments Defining the Rights of Stockholders. Reference is made to
        the Registrant's Registration Statement No. 000-25740 on Form 8-A, as
        amended, including the exhibits thereto, which is incorporated herein by
        reference pursuant to Item 3(c) of this 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 October 21, 1999).
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   Notice of Grant of Stock Option used in connection with the Options
        granted to Mr. Sadr.
99.14   Notice of Grant of Stock Option used in connection with the Options
        granted to Mr. Weisman.
99.15   Form of Stock Option Agreement used in connection with the Options
        granted to Messrs. Sadr and Weisman.
99.16   Form of Written Compensation Agreement for Messrs. Sadr and Weisman.
99.17   Form of Addendum to Stock Option Agreement (Involuntary Termination
        following Change in control) for Messrs. Sadr and Weisman.

               * 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.