<PAGE>   1
                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549



                                    FORM 10-Q

[X]  QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE
     ACT OF 1934. For the quarterly period ended December 31, 1996 

                                       OR

[ ]  TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES
     EXCHANGE ACT OF 1934.

For the transition period from ___________ to_____________


                           Commission File No. 0-14805
                                 MICROCOM, INC.
             (Exact name of registrant as specified in its charter)


               MASSACHUSETTS                                  04-2710644
      (State or other jurisdiction of                      (I.R.S. Employer
      incorporation or organization)                    Identification Number)

           500 RIVER RIDGE DRIVE                              02062-5028
          NORWOOD, MASSACHUSETTS                              (Zip Code)
 (Address of principal executive offices)

       REGISTRANT'S TELEPHONE NUMBER, INCLUDING AREA CODE: (617) 551-1000

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

Indicate by check (x) whether the registrant (1) has filed all reports required
to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during
the preceding 12 months (or for such shorter period that the registrant was
required to file such reports), and (2) has been subject to such filing
requirements for the past 90 days. Yes  x  No 
                                       ---   --- 

Indicate the number of shares outstanding of each of the issuer's classes of
common stock, as of the latest practicable date: As of December 31, 1996,
16,122,226.

--------------------------------------------------------------------------------
<PAGE>   2
                                 MICROCOM, INC.

                                TABLE OF CONTENTS




<TABLE>
<CAPTION>
PART I.  FINANCIAL INFORMATION

<S>                                                                     <C>
CONSOLIDATED BALANCE SHEETS ............................................  3
                                                                         
CONSOLIDATED STATEMENTS OF OPERATIONS ..................................  4
                                                                         
CONSOLIDATED STATEMENTS OF CASH FLOWS ..................................  5
                                                                         
NOTES TO CONSOLIDATED FINANCIAL STATEMENTS .............................  6
                                                                         
MANAGEMENT'S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION              
AND RESULTS OF OPERATIONS ..............................................  7
                                                                         
                                                                         
                                                                         
PART II.  OTHER INFORMATION                                              
                                                                         
EXHIBITS AND REPORTS ON FORM 8-K........................................ 10
                                                                         
SIGNATURES ............................................................. 11
</TABLE>


                                       2
<PAGE>   3
PART I.  FINANCIAL INFORMATION


                                 MICROCOM, INC.

                           CONSOLIDATED BALANCE SHEETS

                                   (Unaudited)

(In thousands)

<TABLE>
<CAPTION>
                                                                   DECEMBER 31, 1996   MARCH 31, 1996
                                                                   -----------------   --------------

                       ASSETS

<S>                                                                <C>                 <C>
Current assets:
  Cash and equivalents ..........................................     $   9,060           $  27,336 
  Accounts receivable, less reserves of $412 and $283 at                               
   December 31, 1996 and March 31, 1996, respectively ...........        50,405              41,811
  Inventories ...................................................        51,911              37,391
  Prepaid expenses and other current assets .....................         1,635               1,695
                                                                      ---------           ---------
   Total current assets .........................................       113,011             108,233
Property and equipment, net .....................................        12,325               7,703
Other assets, net ...............................................        17,731              13,263
                                                                      ---------           ---------
                                                                      $ 143,067           $ 129,199
                                                                      =========           =========
                                                                                       
          LIABILITIES AND STOCKHOLDERS' EQUITY                                         
                                                                                       
Current liabilities:                                                                   
  Current portion of capitalized leases and short-term debt .....     $  11,559           $   1,073
  Accounts payable ..............................................        16,839              19,483
  Accrued expenses ..............................................         3,069               3,348
                                                                      ---------           ---------
   Total current liabilities ....................................        31,467              23,904
                                                                      ---------           ---------
Long-term portion of capitalized leases .........................         3,041               2,186
                                                                      ---------           ---------
                                                                                       
Stockholders' equity:                                                                  
  Common stock, $.01 par value, authorized - 30,000 shares,                            
   issued - 17,103 shares at December 31, 1996, and 16,772 shares                      
   at March 31, 1996 ............................................           171                 168
  Capital in excess of par value ................................       119,560             116,747
  Stock loans - related parties .................................        (2,209)             (2,209)
  Accumulated deficit ...........................................        (6,286)             (9,099)
  Treasury stock, at cost, 981 shares ...........................        (2,613)             (2,613)
  Cumulative translation adjustment .............................           (64)                115
                                                                      ---------           ---------
   Total stockholders' equity ...................................       108,559             103,109
                                                                      ---------           ---------
                                                                      $ 143,067           $ 129,199
                                                                      =========           =========
</TABLE>

The accompanying notes are an integral part of these consolidated financial
statements.


                                       3
<PAGE>   4
                                 MICROCOM, INC.

                      CONSOLIDATED STATEMENTS OF OPERATIONS
         FOR THE THREE AND NINE MONTHS ENDED DECEMBER 31, 1996 AND 1995

                                   (Unaudited)


(In thousands, except per share amounts)

<TABLE>
<CAPTION>
                                                     Three Months Ended            Nine Months Ended
                                                  ------------------------      ------------------------
                                                    1996           1995           1996           1995
                                                  ----------     ---------      ----------    ----------
<S>                                               <C>            <C>            <C>            <C>      
Net sales ......................................  $  46,971      $  39,977      $ 131,181      $ 101,341
Cost of sales ..................................     29,811         23,821         84,626         58,274
                                                  ---------      ---------      ---------      ---------
Gross margin ...................................     17,160         16,156         46,555         43,067
                                                  ---------      ---------      ---------      ---------

Operating expenses:
  Research and development .....................      5,030          4,316         14,274         11,218
  Sales and marketing ..........................      7,415          6,175         22,136         17,411
  General and administrative ...................      1,654          1,750          5,460          4,084
                                                  ---------      ---------      ---------      ---------
   Total operating expenses ....................     14,099         12,241         41,870         32,713
                                                  ---------      ---------      ---------      ---------

Income from operations .........................      3,061          3,915          4,685         10,354
Interest income ................................          3            339             57            878
Interest and other expense, net ................       (847)          (185)        (1,432)        (1,042)
                                                  ---------      ---------      ---------      ---------
Income before income taxes .....................      2,217          4,069          3,310         10,190
Provision for income taxes .....................        333            610            497          1,528
                                                  ---------      ---------      ---------      ---------
Net income .....................................  $   1,884      $   3,459      $   2,813      $   8,662
                                                  =========      =========      =========      =========

Net income per share ...........................  $     .11      $     .21      $     .17      $     .57
                                                  =========      =========      =========      =========

Weighted average number of shares outstanding ..     16,790         16,715         16,818         15,196
                                                  =========      =========      =========      =========
</TABLE>


The accompanying notes are an integral part of these consolidated financial
statements.


                                       4
<PAGE>   5
                                 MICROCOM, INC.

                      CONSOLIDATED STATEMENTS OF CASH FLOWS
              FOR THE NINE MONTHS ENDED DECEMBER 31, 1996 AND 1995


                                   (Unaudited)

(In thousands)

<TABLE>
<CAPTION>
                                                                         NINE MONTHS ENDED
                                                                       ----------------------
                                                                         1996         1995
                                                                       --------      --------

<S>                                                                    <C>           <C>
Cash flows from operating activities:
  Net income .....................................................     $  2,813      $  8,662

Adjustments to reconcile net income to net cash used in
 operating activities:
   Depreciation and amortization .................................        8,170         5,485
   Changes in assets and liabilities:
     Accounts receivable, net ....................................       (9,344)      (15,383)
     Inventories .................................................      (14,520)       (7,125)
     Prepaid expenses and other current assets ...................           60          (602)
     Accounts payable and accrued expenses .......................       (2,923)        8,281
                                                                       --------      --------
      Net cash used in operating activities ......................      (15,744)         (682)
                                                                       --------      --------

Cash flows used in investing activities:
   Capitalized software development costs and purchased technology       (5,531)       (4,408)
   Purchase of property and equipment ............................       (7,662)       (3,077)
   Other assets and equity investments ...........................       (2,757)         (117)
                                                                       --------      --------
      Net cash used in investing activities ......................      (15,950)       (7,602)
                                                                       --------      --------

Cash flows provided by financing activities:
  Borrowings (payments) under the revolving credit line, net .....        9,768       (12,020)
  Exercise of stock options and employee stock purchase plan .....        2,256         3,895
  Borrowings on capitalized leases ...............................        1,573         2,687
  Proceeds from public offering, net .............................           --        50,418
  Repayment of stock loans .......................................           --           461
  Banker acceptance on inventory purchases .......................           --          (195)
                                                                       --------      --------
      Net cash provided by financing activities ..................       13,597        45,246
                                                                       --------      --------

Effect of exchange rates on cash .................................         (179)           --
                                                                       --------      --------

Net (decrease) increase in cash and equivalents ..................      (18,276)       36,962
Cash and equivalents at beginning of period ......................       27,336           863
                                                                       --------      --------
Cash and equivalents at end of period ............................     $  9,060      $ 37,825
                                                                       ========      ========
</TABLE>


The accompanying notes are an integral part of these consolidated financial
statements.


                                       5
<PAGE>   6
                                 MICROCOM, INC.

                   NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

                                   (Unaudited)

(in thousands)



NOTE 1.  BASIS FOR PRESENTATION

The consolidated balance sheet as of December 31, 1996, and the related
consolidated statements of operations and cash flows for the three and nine
months ended December 31, 1996 and 1995, are unaudited. In the opinion of
management, all adjustments necessary for the fair presentation of such
financial statements have been included, such adjustments consisted only of
normal recurring items. Interim results are not necessarily indicative of
results for a full fiscal year.

The financial statements are presented as permitted by Form 10-Q and do not
contain certain information included in the Company's annual consolidated
financial statements.


NOTE 2.  INVENTORIES

<TABLE>
<CAPTION>
                                              DECEMBER 31, 1996      MARCH 31, 1996
                                              -----------------      --------------

<S>                                           <C>                    <C>
Raw materials ........................              $14,629              $ 9,601
Finished goods .......................               37,282               27,790
                                                    -------              -------
                                                    $51,911              $37,391
                                                    =======              =======
</TABLE>


NOTE 3.  PROPERTY AND EQUIPMENT

<TABLE>
<CAPTION>
                                                                                Depreciable Life
                                           DECEMBER 31, 1996   MARCH 31, 1996      in Years
                                           -----------------   --------------   ----------------

<S>                                        <C>                 <C>              <C>
Computer equipment and software .........       $ 15,683          $ 11,029             2-3
Machinery and equipment .................          4,217             3,090             3-7
Furniture and fixtures ..................          2,227             1,659               8
Leasehold improvements ..................          2,522             2,327        Life of Lease
                                                --------          --------      
                                                  24,649            18,105      
Accumulated depreciation and amortization        (12,324)          (10,402)     
                                                --------          --------
                                                $ 12,325          $  7,703      
                                                ========          ========      
</TABLE>


                                       6
<PAGE>   7
                                        
                                 MICROCOM, INC.
           MANAGEMENT'S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION
                            AND RESULTS OF OPERATIONS

RESULTS OF OPERATIONS

Net Sales - Net sales for the three and nine month periods ended December 31,
1996, were $46,971,000 and $131,181,000, respectively, 17% and 29% increases
from the same periods in fiscal year 1996. These increases were primarily
attributable to increased sales of central site products which accounted for
76% and 59% of net sales for the three and nine month periods of this fiscal
year. The growth within the central site segment was primarily due to sales of 
customized central site technology and the ISPorte, a recently announced
managed modem chassis system. These increases in central site sales were offset
by the decline in sales of remote site V.34 modems, coupled with decreased
sales of HDMS within the central site telecommunications market. For the past
year the Company has been signing strategic agreements with industry leading
original equipment manufacturer (OEM) customers. The expansion of the OEM
business has resulted in significant central site technology sales. Sales to
OEM customers accounted for 28% of first quarter net sales, 42% of second
quarter net sales and 60% of third quarter net sales. Two of the Company's OEM
customers accounted for 53% of the Company's sales for the three months ended
December 31, 1996. One customer accounted for 41% while the other accounted for
12%. International sales for the three and nine month periods of fiscal 1997
were $9,902,000 and $42,816,000 as compared to $24,162,000 and $47,563,000 for
the same periods last year. These decreases in international sales were
primarily due to decreased sales of remote site V.34 modem products, especially
in the Asia Pacific, Japanese and South African markets.

Gross Margin - Gross margins for the three and nine month periods ended
December 31, 1996, were 37% and 36%, respectively, of net sales as compared to
40% and 43% for the same periods last year. The decreases were primarily due to
increased unit volume of lower margin customized modem boards and lower average
selling price of the remote site V.34 modem products, coupled with the decline
in sales of higher margin HDMS products. Due to the change in product mix the
Company expects continued pressure on gross margins.

Research and Development - During the three and nine month periods ended
December 31, 1996, research and development expenses increased $714,000 and
$3,056,000, respectively, or 17% and 27% from the same periods last year. These
increases reflect the Company's continued investment in new and existing
technologies and were principally due to the hiring of additional engineering
personnel and increased consulting and contract professional fees.

Sales and Marketing - In the three and nine month periods ended December 31,
1996, sales and marketing expenses increased by $1,204,000 and $4,725,000,
respectively, or 20% and 27% from the same periods last year. The increases were
directly related to the expansion of the Company's international distribution
channels and marketing programs.

General and Administrative - During the three and nine month periods ended
December 31, 1996, general and administrative expenses were $1,654,000 and
$5,460,000, respectively, as compared to $1,750,000 and $4,084,000,
respectively, in the previous fiscal year. The Company's goal is to maintain
general and administrative spending at approximately 4% of net sales.

Interest Income and Expense - In the three and nine month periods ended December
31, 1996, interest income decreased $336,000 and $821,000, respectively.
Additionally, interest and other expense increased $662,000 and $390,000 for the
same periods of this fiscal year. Both the decrease in interest income and the
increase in interest and other expense were primarily a result of increased
borrowings under the Company's revolving credit facility, to meet working
capital requirements, during the first nine months of fiscal 1997.

Income Taxes - The Company's effective tax rate was 15% for both periods
reported. The difference between the statutory rate and the effective tax rate
reflects the utilization of a portion of the Company's net operating loss carry
forwards. At December 31, 1996, the Company had available $17,400,000 in net
operating loss carry forwards, which may be used to offset future taxable
income, and $4,719,000 in research and development and other tax credit carry
forwards, which may be used to offset future taxes payable. These carry forwards
expire through 2009 and are subject to review and possible adjustment by the
Internal Revenue Service.


                                       7
<PAGE>   8
           MANAGEMENT'S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION
                            AND RESULTS OF OPERATIONS


LIQUIDITY AND CAPITAL RESOURCES

The Company's cash and equivalents decreased by $18,276,000 in the first nine
months of fiscal 1997. The decrease from the beginning of fiscal 1997 was
primarily due to the use of $15,744,000 in cash in operating activities,
specifically, increases in accounts receivable of $9,344,000, inventories of
$14,520,000, and a decrease in accounts payable and accrued expenses of
$2,923,000. The increase in accounts receivable is a combination of a 29%
increase in net sales in the first nine months of fiscal 1997, along with the
growth in receivables with respect to distribution net sales where payment
cycles are longer. The increase in inventory reflects an anticipated increase
in net sales associated with new product offerings in the central site product
line, coupled with decreased sales of remote site V.34 modem products and HDMS
central site products. The Company has implemented marketing programs to 
reduce inventory balances of older product offerings. Cash flows used in
investing activities in the first nine months of fiscal 1997 included continued
investments in software development costs of $5,531,000, and purchases of
property and equipment of $7,662,000, in both instances to support the
development of new products and growth of the Company. In addition, issuance of
additional shares of common stock under the Company's stock plans resulted in
proceeds of $2,256,000.

As of December 31, 1996, the Company had $9,060,000 in cash and equivalents. In
addition, the Company had a bank revolving credit facility which allowed the
Company to borrow up to an amount (the "Maximum Borrowing Amount") equal to the
lesser of (i) $45,000,000 or (ii) an amount based on the Company's eligible
accounts receivable. The Maximum Borrowing Amount is reduced by amounts which
may be drawn on outstanding letters of credit. Under the terms of the credit
facility, interest is at the bank's prime rate (8 1/4 % at December 31, 1996)
and the Company is required to comply with certain covenants. At December 31,
1996, the Company was contingently liable with respect to $2,500,000 in
outstanding letters of credit and its bank credit availability was
approximately $14,095,000. At December 31, 1996, there were $9,768,000 in
borrowings under the credit facility and the Company was in compliance with all
covenants.

Since its inception, the Company has met its liquidity requirements through cash
provided by operations, product line dispositions, public and private stock
offerings, lease arrangements for facilities and equipment and short-term
borrowings from banks. Management believes that its cash and equivalents, line
of credit availability, and cash provided by operations will be adequate to meet
the Company's liquidity requirements for the immediate future.


FOREIGN CURRENCY HEDGING

To date, all of the Company's transactions (including customer sales and
purchases from vendors) have been denominated in U.S. dollars, except for
transactions in Japan and an immaterial amount of transactions in the U.K.. The
Company's policy is to hedge the currency risk by entering into forward
contracts. The gains or losses on such contracts are deferred until the
contracts are settled and are then recognized as other income or expense. As of
December 31, 1996, the Company had $3,572,000 in foreign currency contracts
outstanding. The Company had no material unrealized gains or losses on these
contracts.


INDUSTRY TRENDS

In July, 1996 the Company's major OEM customer, Cisco Systems, Inc. (CISCO),
announced the acquisition of a company which competes in certain areas with the
Company's central site technology business. This acquisition is reflective of a
continuing trend toward consolidation in the industry which makes products for
distributed enterprise-wide computing networks ("intranets") and online
services supporting access to the Internet. Although the Company's relationship
with Cisco remains strong and management believes that the Company's focus on
expanding its OEM relationships is a sound strategy for growth, there can be no
assurance that such consolidations will not materially and adversely affect its
OEM business, results of operations or financial condition.


                                       8
<PAGE>   9
CAUTIONARY STATEMENT

When used anywhere in this Form 10-Q, in future filings by the Company with the
Securities and Exchange Commission, in the Company's press releases and in oral
statements made with the approval of an authorized executive officer of the
Company, the words or phrases "will likely result", "are expected to", "will
continue", "is anticipated", "estimated", "project", or "outlook" or similar
expressions (including confirmations by an authorized executive officer of the
Company of any such expressions made by a third party with respect to the
Company) are intended to identify "forward-looking statements" within the
meaning of the Private Securities Litigation Reform Act of 1995. The Company
wishes to caution readers not to place undue reliance on any such forward
looking statements, which speak only as of the date made. Such statements are
subject to certain risks and uncertainties that could cause actual results to
differ materially from historical earnings and those presently anticipated or
projected. Certain of such risks and uncertainties are described above and in
the risk factors set forth in Part I of the Company's Form 10K for the fiscal
year ended March 31, 1996 filed with the Securities and Exchange Commission,
including, among others, the risks associated with (i) the Company's focus on
expanding its OEM relationships as described above in Industry Trends and the
Company's reliance on indirect distribution channels generally, (ii) the need to
develop new products and respond to rapid changes in technology, (iii) the
highly competitive markets in which the Company participates, (iv) the Company's
efforts to generate and maintain sales to telecommunications carriers, (v) the
Company's dependence on suppliers and subcontractors, (vi) the Company's
dependence on and the need to protect its proprietary technology, (vii) the
Company's dependence on international operations, and (viii) the Company's focus
on central site and remote access markets. The Company specifically declines any
obligation to publicly release the result of any revisions which may be made to
any forward-looking statements to reflect anticipated or unanticipated events or
circumstances occurring after the date of such statements.


                                       9
<PAGE>   10
PART II.  OTHER INFORMATION



ITEM 6.  EXHIBITS AND REPORTS ON FORM 8-K

         (a)  EXHIBITS.

               Exhibit 11.0 -  Calculation of net income per share
               Exhibit 27.0 -  Financial Data Schedule

         (b)  REPORTS ON FORM 8-K.

               No reports on Form 8-K were filed by the Company during the
period covered by this report.



                                       10
<PAGE>   11
                                   SIGNATURES





Pursuant to the requirements of the Securities Exchange Act of 1934, the
registrant has duly caused this report to be signed on its behalf by the
undersigned thereunto duly authorized.




<TABLE>
<S>                                      <C> 
DATE:        February 14, 1997           BY:             /s/  Lewis A. Bergins
     ---------------------------------       ----------------------------------------------
                                                       Lewis A. Bergins, President
                                                  Chief Executive Officer and Director





DATE:        February 14, 1997           BY:             /s/  Peter J. Minihane
     ---------------------------------       ----------------------------------------------
                                               Peter J. Minihane, Executive Vice President
                                                   Chief Financial Officer and Treasurer
</TABLE>


                                       11