<PAGE>   1

    As filed with the Securities and Exchange Commission on October 12, 1999

                                        Registration Statement No. 333-_________
================================================================================

                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549

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

                                    FORM S-8
                             REGISTRATION STATEMENT
                                      UNDER
                           THE SECURITIES ACT OF 1933

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

                                BROOKTROUT, INC.
             (Exact Name of Registrant as Specified in Its Charter)


     MASSACHUSETTS                                       04-2184792
(State of Organization)                     (I.R.S. Employer Identification No.)

                                410 FIRST AVENUE
                          NEEDHAM, MASSACHUSETTS 02494
                    (Address of Principal Executive Offices)

                                BROOKTROUT, INC.
                      1992 STOCK INCENTIVE PLAN, AS AMENDED
                            (Full Title of the Plans)

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


                                  ERIC R. GILER
                                    President
                                Brooktrout, Inc.
                                410 First Avenue
                          Needham, Massachusetts 02494
                                 (781) 449-4100
 (Name, Address and Telephone Number, including Area Code, of Agent for Service)

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


                                  With copy to:
                             THOMAS P. STORER, P.C.
                           GOODWIN, PROCTER & HOAR LLP
                                 Exchange Place
                        Boston, Massachusetts 02109-2881
                                 (617) 570-1000

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


                         CALCULATION OF REGISTRATION FEE

<TABLE>
<CAPTION>
====================================================================================================================================
Title of Securities To Be          Amount to be              Proposed Maximum            Proposed Maximum              Amount of
        Registered                Registered (1)        Offering Price Per Share(2)  Aggregate Offering Price       Registration Fee
------------------------------------------------------------------------------------------------------------------------------------
<S>                               <C>                             <C>                       <C>                          <C>
      Common Stock,               300,000 shares                  $12.03                    $3,609,000                   $1,004
      $.01 par value
====================================================================================================================================
</TABLE>

(1)  Pursuant to Rule 416(c) under the Securities Act of 1933, as amended (the
     "Securities Act"), this registration statement also covers an indeterminate
     amount of interests to be offered or sold pursuant to the employee benefit
     plans described herein.

(2)  This estimate is made pursuant to Rule 457(c) and (h) under the Securities
     Act solely for the purposes of determining the amount of the registration
     fee. The registration fee is based upon the average of the high and low
     prices for the Registrant's Common Stock, par value $.01 per share, as
     reported on the NASDAQ National Market on October 11, 1999.

================================================================================

<PAGE>   2




                                     PART II

               INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

        Pursuant to Instruction E of Form S-8, Brooktrout, Inc. (the
"Registrant") hereby incorporates by reference the Registration Statements on
Form S-8 dated December 10, 1992 as filed with the Commission on December 17,
1992, File No. 33-55900 and dated September 4, 1998 as filed with the Commission
on September 4, 1998, File No.
333-62959.


ITEM 8.  EXHIBITS.

       The following is a complete list of exhibits filed or incorporated by
reference as part of this registration statement.

Exhibits

  4.1     Brooktrout, Inc. 1992 Stock Incentive Plan, as amended, previously
          filed as Exhibit 10.1 to Brooktrout, Inc.'s Registration Statement on
          Form S-8 filed with the Commission on September 19, 1996, File No.
          333-12313
  4.2     Second Amendment to Brooktrout, Inc. 1992 Stock Incentive Plan
          previously filed as Exhibit 4.2 to Brooktrout, Inc.'s Registration
          Statement on Form S-8 filed with the Commission on September 4, 1998,
          File No.333-62959
  4.3     Third Amendment to Brooktrout, Inc. 1992 Stock Incentive Plan
  5.1     Opinion of Goodwin, Procter & Hoar LLP as to the legality of the
          securities being registered
 23.1     Consent of Goodwin, Procter & Hoar LLP (included in Exhibit 5.1)
 23.2     Consent of Deloitte & Touche LLP, Independent Auditors
 24.1     Powers of Attorney (included on signature page to this registration
          statement)



                                        2

<PAGE>   3


                                   SIGNATURES

         Pursuant to the requirements of the Securities Act of 1933, Brooktrout,
Inc. 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 Needham, Commonwealth of Massachusetts on this 12th
day of October, 1999.

                                     Brooktrout, Inc.

                                     By:          /s/ Eric R. Giler
                                        ----------------------------------------
                                                      Eric R. Giler
                                                        President


                                POWER OF ATTORNEY

         KNOW ALL MEN BY THESE PRESENTS, that each individual whose signature
appears below constitutes and appoints each of Eric R. Giler, David W. Duehren
and Robert C. Leahy, and each of them acting singly, such person's true and
lawful attorney-in-fact and agent, with full power of substitution and
resubstitution, for such person and in such person's name, place and stead, in
any and all capacities, to sign any and all amendments (including post-effective
amendments) to this registration statement, and to file the same, with all
exhibits thereto, and all documents in connection therewith, with the Securities
and Exchange Commission, granting unto each said attorney-in-fact and agent full
power and authority to do and perform each and every act and thing requisite and
necessary to be done in and about the premises, as fully to all intents and
purposes as such person might or could do in person, hereby ratifying and
confirming all that any said attorney-in-fact and agent, or any substitute or
substitutes of any of them, may lawfully do or cause to be done by virtue
hereof.

         Pursuant to the requirements of the Securities Act of 1933, this
registration statement has been signed below by the following persons in the
capacities and on the date indicated.

<TABLE>
<CAPTION>

          SIGNATURE                               TITLE                                      DATE
          ---------                               -----                                      ----

<S>                                   <C>                                             <C>
    /s/ Eric R. Giler                 President and Director                          October 12, 1999
------------------------------        (Principal Executive Officer)
        Eric R. Giler

    /s/ David W. Duehren              Vice President of Research and                  October 12, 1999
------------------------------        Development, Clerk and Director
        David W. Duehren

    /s/ Robert C. Leahy               Vice President of Finance and Operations,       October 12, 1999
------------------------------        and Treasurer (Principal Financial and
        Robert C. Leahy               Accounting Officer)


    /s/ Patrick T. Hynes              Vice President of Advanced Product              October 12, 1999
------------------------------        Engineering and Director
        Patrick T. Hynes

    /s/ Robert G. Barrett             Director                                        October 12, 1999
------------------------------
        Robert G. Barrett

    /s/ David L. Chapman              Director                                        October 12, 1999
------------------------------
        David L. Chapman


------------------------------        Director                                        October __, 1999
        W. Brooke Tunstall
</TABLE>



                                        3

<PAGE>   4


                                  EXHIBIT INDEX


Exhibit No.    Description
-----------    -----------


4.3            Third Amendment to Brooktrout, Inc. 1992 Stock Incentive Plan


5.1            Opinion of Goodwin, Procter & Hoar LLP as to the legality of the
               securities being registered

23.1           Consent of Goodwin, Procter & Hoar LLP (included in Exhibit 5.1)

23.2           Consent of Deloitte & Touche LLP

24.1           Powers of Attorney (included on signature pages to this
               Registration Statement)




                                        4
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{"company-data": {"conformed-name": "BROOKTROUT TECHNOLOGY INC", "cik": "0000754516", "assigned-sic": "3661", "irs-number": "042814792", "state-of-incorporation": "MA", "fiscal-year-end": "1231"}, "filing-values": {"form-type": "S-8", "act": "33", "file-number": "333-88803", "film-number": "99726857"}, "business-address": {"street1": "410 FIRST AVE", "city": "NEEDHAM", "state": "MA", "zip": "02494", "phone": "7814494100"}, "mail-address": {"street1": "410 FIRST", "city": "NEEDHAM", "state": "MA", "zip": "02494"}}
1

    As filed with the Securities and Exchange Commission on October 12, 1999

                                        Registration Statement No. 333-_________
================================================================================

                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549

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

                                    FORM S-8
                             REGISTRATION STATEMENT
                                      UNDER
                           THE SECURITIES ACT OF 1933

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

                                BROOKTROUT, INC.
             (Exact Name of Registrant as Specified in Its Charter)

     MASSACHUSETTS                                       04-2184792
(State of Organization)                     (I.R.S. Employer Identification No.)

                                410 FIRST AVENUE
                          NEEDHAM, MASSACHUSETTS 02494
                    (Address of Principal Executive Offices)

                                BROOKTROUT, INC.
                      1992 STOCK INCENTIVE PLAN, AS AMENDED
                            (Full Title of the Plans)

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

                                  ERIC R. GILER
                                    President
                                Brooktrout, Inc.
                                410 First Avenue
                          Needham, Massachusetts 02494
                                 (781) 449-4100
 (Name, Address and Telephone Number, including Area Code, of Agent for Service)

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

                                  With copy to:
                             THOMAS P. STORER, P.C.
                           GOODWIN, PROCTER & HOAR LLP
                                 Exchange Place
                        Boston, Massachusetts 02109-2881
                                 (617) 570-1000

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

                         CALCULATION OF REGISTRATION FEE
====================================================================================================================================
Title of Securities To Be          Amount to be              Proposed Maximum            Proposed Maximum              Amount of
        Registered                Registered (1)        Offering Price Per Share(2)  Aggregate Offering Price       Registration Fee
------------------------------------------------------------------------------------------------------------------------------------
Common Stock,               300,000 shares                  $12.03                    $3,609,000                   $1,004
      $.01 par value
====================================================================================================================================
(1)  Pursuant to Rule 416(c) under the Securities Act of 1933, as amended (the
     "Securities Act"), this registration statement also covers an indeterminate
     amount of interests to be offered or sold pursuant to the employee benefit
     plans described herein.

(2)  This estimate is made pursuant to Rule 457(c) and (h) under the Securities
     Act solely for the purposes of determining the amount of the registration
     fee. The registration fee is based upon the average of the high and low
     prices for the Registrant's Common Stock, par value $.01 per share, as
     reported on the NASDAQ National Market on October 11, 1999.

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

                                     PART II

               INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

        Pursuant to Instruction E of Form S-8, Brooktrout, Inc. (the
"Registrant") hereby incorporates by reference the Registration Statements on
Form S-8 dated December 10, 1992 as filed with the Commission on December 17,
1992, File No. 33-55900 and dated September 4, 1998 as filed with the Commission
on September 4, 1998, File No.
333-62959.

ITEM 8.  EXHIBITS.

       The following is a complete list of exhibits filed or incorporated by
reference as part of this registration statement.

Exhibits

  4.1     Brooktrout, Inc. 1992 Stock Incentive Plan, as amended, previously
          filed as Exhibit 10.1 to Brooktrout, Inc.'s Registration Statement on
          Form S-8 filed with the Commission on September 19, 1996, File No.
          333-12313
  4.2     Second Amendment to Brooktrout, Inc. 1992 Stock Incentive Plan
          previously filed as Exhibit 4.2 to Brooktrout, Inc.'s Registration
          Statement on Form S-8 filed with the Commission on September 4, 1998,
          File No.333-62959
  4.3     Third Amendment to Brooktrout, Inc. 1992 Stock Incentive Plan
  5.1     Opinion of Goodwin, Procter & Hoar LLP as to the legality of the
          securities being registered
 23.1     Consent of Goodwin, Procter & Hoar LLP (included in Exhibit 5.1)
 23.2     Consent of Deloitte & Touche LLP, Independent Auditors
 24.1     Powers of Attorney (included on signature page to this registration
          statement)

                                        2
3

                                   SIGNATURES

         Pursuant to the requirements of the Securities Act of 1933, Brooktrout,
Inc. 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 Needham, Commonwealth of Massachusetts on this 12th
day of October, 1999.

                                     Brooktrout, Inc.

                                     By:          /s/ Eric R. Giler
                                        ----------------------------------------
                                                      Eric R. Giler
                                                        President

                                POWER OF ATTORNEY

         KNOW ALL MEN BY THESE PRESENTS, that each individual whose signature
appears below constitutes and appoints each of Eric R. Giler, David W. Duehren
and Robert C. Leahy, and each of them acting singly, such person's true and
lawful attorney-in-fact and agent, with full power of substitution and
resubstitution, for such person and in such person's name, place and stead, in
any and all capacities, to sign any and all amendments (including post-effective
amendments) to this registration statement, and to file the same, with all
exhibits thereto, and all documents in connection therewith, with the Securities
and Exchange Commission, granting unto each said attorney-in-fact and agent full
power and authority to do and perform each and every act and thing requisite and
necessary to be done in and about the premises, as fully to all intents and
purposes as such person might or could do in person, hereby ratifying and
confirming all that any said attorney-in-fact and agent, or any substitute or
substitutes of any of them, may lawfully do or cause to be done by virtue
hereof.

         Pursuant to the requirements of the Securities Act of 1933, this
registration statement has been signed below by the following persons in the
capacities and on the date indicated.
SIGNATURE                               TITLE                                      DATE
          ---------                               -----                                      ----
/s/ Eric R. Giler                 President and Director                          October 12, 1999
------------------------------        (Principal Executive Officer)
        Eric R. Giler

    /s/ David W. Duehren              Vice President of Research and                  October 12, 1999
------------------------------        Development, Clerk and Director
        David W. Duehren

    /s/ Robert C. Leahy               Vice President of Finance and Operations,       October 12, 1999
------------------------------        and Treasurer (Principal Financial and
        Robert C. Leahy               Accounting Officer)

    /s/ Patrick T. Hynes              Vice President of Advanced Product              October 12, 1999
------------------------------        Engineering and Director
        Patrick T. Hynes

    /s/ Robert G. Barrett             Director                                        October 12, 1999
------------------------------
        Robert G. Barrett

    /s/ David L. Chapman              Director                                        October 12, 1999
------------------------------
        David L. Chapman

------------------------------        Director                                        October __, 1999
        W. Brooke Tunstall
3
4

                                  EXHIBIT INDEX

Exhibit No.    Description
-----------    -----------

4.3            Third Amendment to Brooktrout, Inc. 1992 Stock Incentive Plan

5.1            Opinion of Goodwin, Procter & Hoar LLP as to the legality of the
               securities being registered

23.1           Consent of Goodwin, Procter & Hoar LLP (included in Exhibit 5.1)

23.2           Consent of Deloitte & Touche LLP

24.1           Powers of Attorney (included on signature pages to this
               Registration Statement)

                                        4