<PAGE>   1
                                                                     EXHIBIT 4.2


                   AMENDMENT NO. 1 TO STOCKHOLDERS' AGREEMENT


               This is Amendment No. 1 (this "Amendment"), dated as of July 19,
2000, to the Stockholders Agreement dated as of May 10, 1999 (the "Stockholders
Agreement"), among Time Warner Telecom Inc., a Delaware corporation (the
"Company"), Time Warner Companies, Inc., a Delaware corporation ("TWX"),
American Television and Communications Corporation, a Delaware corporation
("ATC"), Warner Communications Inc., a Delaware corporation ("WCI"), TW/TAE,
Inc., a Delaware corporation ("TW/TAE"), FibrCOM Holdings, L.P., a Delaware
limited partnership that is owned by TW/KBLCOM Inc., a Delaware corporation
("TW/KBLCOM"), Paragon Communications, a Colorado general partnership ("Paragon"
and, together with TWX, ATC, WCI, TWI/TAE and TW/KBLCOM, the "TW Stockholders"),
MediaOne of Colorado, Inc., a Colorado corporation (the "MediaOne Stockholder"),
and Advance/Newhouse Partnership, a New York general partnership ("A/N").
Capitalized terms used in this Amendment and not otherwise defined herein shall
have the meaning assigned thereto in the Stockholders Agreement.

               WHEREAS, the parties to the Stockholders Agreement desire to
amend certain provisions of the Stockholders Agreement;

               WHEREAS, all of the shares of Common Stock of the Company held by
the MediaOne Stockholder were transferred to MediaOne Holdings II, Inc. pursuant
to an Assignment and Assumption Agreement dated February 11, 2000;

               WHEREAS, Section 2.5 of the Stockholders Agreement provides that
in the event the Company takes any action which changes the number of shares of
Common Stock of the Company outstanding the ownership thresholds for nominations
of directors must be adjusted, and such ownership thresholds have been and will
continue to be adjusted from time to time;

               WHEREAS, the number of shares of Common Stock of the Company
outstanding has increased due to the issuance of Class A Common Stock, par value
$.01 per share ("Class A Common Stock") (i) in connection with the acquisition
of Internet Connect, Inc.; (ii) in connection with the acquisition of MetroComm,
Inc.; (iii) in an initial public
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                                                                               2


offering pursuant to the Underwriting Agreement dated as of May 11, 1999 and
(iv) in connection with the exercise of stock options;

               WHEREAS, as of June 30, 2000, the Company had 33,177,815 shares
of Class A Common Stock and 72,226,500 shares of Class B Common Stock, par value
$.01 per share outstanding;

               WHEREAS, Annex A attached hereto sets forth the calculation of
the Ownership Percentages required for nominations of directors as provided in
the Stockholders Agreement;

               NOW, THEREFORE, in consideration of the premises and other good
and valuable consideration, the adequacy and receipt of which is hereby
acknowledged, the parties hereto, intending to be legally bound, agree as
follows:

               1. Amendment to Sections 2.1(c)(i)(A) through (C) of the
Stockholders Agreement. Sections 2.1(c)(i)(A) through (C) of the Stockholders
Agreement are hereby amended and restated in their entirety to read as follows:

               "(c)  The Agreed Nominees shall be designated as follows:

               (i) (A) So long as the TW Stockholder Group has an Ownership
        Percentage which is greater than or equal to 14.55% (as adjusted from
        time to time pursuant to Section 2.5), the TW Stockholder Group shall
        have the right to designate four Agreed Nominees. If the TW Stockholder
        Group has an Ownership Percentage which is less than 14.55% (as adjusted
        from time to time pursuant to Section 2.5), the TW Stockholder Group
        shall have the right to designate a number of Agreed Nominees determined
        in accordance with the following table (with the percentages set forth
        in such table being adjusted from time to time pursuant to Section 2.5).

<TABLE>
<CAPTION>
                TW Stockholder Group                      Number of
                Ownership Percentage                      Agreed Nominees
                --------------------                      ---------------
<S>                                                       <C>
                14.55% or greater                         4
                12.12% to 14.54%                          3
                9.70% to 12.11%                           2
                7.28% to 9.69%                            1
                less than 7.28%                           0
</TABLE>

<PAGE>   3
                                                                               3


               (B) So long as the TW Stockholder Group has an Ownership
        Percentage which is greater than or equal to 14.55% (as adjusted from
        time to time pursuant to Section 2.5), the MediaOne Stockholder Group
        shall have the right to designate a number of Agreed Nominees determined
        in accordance with the following table (with the percentages set forth
        in such table being adjusted from time to time pursuant to Section 2.5).

<TABLE>
<CAPTION>
                Media One
                Stockholder Group                         Number of
                Ownership Percentage                      Agreed Nominees
                --------------------                      ---------------
<S>                                                       <C>
                7.28% or greater                          3
                less than 7.28%                           0
</TABLE>

        If the TW Stockholder Group has an Ownership Percentage which is less
        than 18.77% (as adjusted from time to time pursuant to Section 2.5), the
        MediaOne Stockholder Group shall have the right to designate a number of
        Agreed Nominees determined in accordance with the following table (with
        the percentages set forth in such table being adjusted from time to time
        pursuant to Section 2.5).

<TABLE>
<CAPTION>
                Media One
                Stockholder Group                         Number of
                Ownership Percentage                      Agreed Nominees
                --------------------                      ---------------
<S>                                                       <C>
                14.55% or greater                         3
                10.91% to 14.54%                          2
                7.28% to 10.90%                           1
                less than 7.28%                           0
</TABLE>

               (C) So long as the A/N Stockholder Group has an Ownership
        Percentage which is greater than or equal to 7.28% (as adjusted from
        time to time pursuant to Section 2.5), the A/N Stockholder Group shall
        have the right to designate one Agreed Nominee. If the A/N Stockholder
        Group has an Ownership Percentage of less than 7.28% (as adjusted from
        time to time pursuant to
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                                                                               4


        Section 2.5), the A/N Stockholder Group shall not have the right to
        designate any Agreed Nominees."

               2.  Amendment to Section 2.1(c)(iii) of the Stockholders
        Agreement.  Section 2.1(c)(iii) of the Stockholders Agreement is hereby
        amended and restated in its entirety to read as follows:

               "(iii) Three individuals nominated by the Nominating Committee
        shall be Agreed Nominees if such individuals would be Independent
        Directors at the time of their election and are approved by a majority
        of the members of the Nominating Committee."

               3.  Effectiveness.  The amendments set forth in Sections 1 and 2
        hereof shall become effective upon execution of a counterpart of this
        Amendment by each of the undersigned parties.  Upon such effectiveness:

               (i)  all references in any document to the Stockholders Agreement
        shall be deemed to be references to the Stockholders Agreement as
        amended hereby; and

               (ii) except as specifically amended hereby, the Stockholders
        Agreement shall continue in full force and effect in accordance with the
        provisions thereof, and as used therein, respectively, the terms
        "Agreement", "herein", "hereof", and words of similar import shall,
        unless the context otherwise requires, refer to the Stockholders
        Agreement as amended hereby.

               4. Further Assurances. From time to time upon the request of any
party, each party hereto shall execute, deliver and acknowledge any and all such
further documents and instruments and do such further acts and things as the
other party hereto may reasonably request to evidence or effectuate more
effectively the terms of and intent of the parties contemplated by this
Amendment.

               This Amendment, which may be executed in two or more
counterparts, all of which shall be considered one and the same agreement, shall
be governed by, and construed in accordance with, the law of the State of New
York without reference to choice of law principles, including all matters of
construction, validity and performance except to the extent the laws of Delaware
are mandatorily applicable.

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                                                                               5


               IN WITNESS WHEREOF, the parties hereto have caused this Amendment
No. 1 to be duly executed as of the date and year first written above.



                                    TIME WARNER COMPANIES, INC.


                                    By:/s/ Spencer B. Hays
                                       --------------------------
                                       Name:  Spencer B. Hays
                                       Title: Vice President


                                    AMERICAN TELEVISION AND
                                    COMMUNICATIONS CORPORATION


                                    By:/s/ Spencer B. Hays
                                       --------------------------
                                       Name:  Spencer B. Hays
                                       Title: Vice President


                                    WARNER COMMUNICATIONS INC.


                                    By:/s/ Spencer B. Hays
                                       --------------------------
                                       Name:  Spencer B. Hays
                                       Title: Vice President


                                    TW/TAE, INC.


                                    By:/s/ Spencer B. Hays
                                       --------------------------
                                       Name:  Spencer B. Hays
                                       Title: Vice President
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                                                                               6


                                    FIBRCOM HOLDINGS, L.P.

                                    By:     FIBRCOM INCORPORATED,
                                            General Partner


                                            By: /s/  Spencer B. Hays
                                                ---------------------
                                                Name:  Spencer B. Hays
                                                Title: Vice President


                                    PARAGON COMMUNICATIONS

                                    By:     KBL COMMUNICATIONS, INC.,
                                            Managing General Partner


                                            By:/s/ Spencer B. Hays
                                               ----------------------
                                               Name:  Spencer B. Hays
                                               Title: Vice President


                                    MEDIAONE HOLDINGS II, INC.


                                    By:/s/ William R. Bechstein
                                       ---------------------------
                                       Name:  William R. Bechstein
                                       Title: Secretary


                                    ADVANCE/NEWHOUSE PARTNERSHIP

                                    By:     ADVANCE COMMUNICATION CORP.
                                            General Partner

                                            By:/s/ Robert J. Miron
                                               ----------------------
                                               Name:  Robert J. Miron
                                               Title: President
<PAGE>   7
                                                                               7


                                                                         ANNEX A

                      CALCULATION OF OWNERSHIP PERCENTAGES

               This Annex A sets forth the calculation of the Ownership
Percentages required for nominations of directors as provided in Section
2.1(c)(i)(A) through (C) of the Stockholders Agreement. Reference is made to the
letter notice dated March 10, 2000 (the "Letter"), attached hereto, which served
as the initial notice of adjustment of the Ownership Percentages contained in
the Stockholders Agreement.

               As of March 10, 2000, the Company had 23,507,707 shares of Class
A Common Stock and 81,250,000 shares of Class B Common Stock outstanding. As of
June 30, 2000, the Company had 33,177,815 shares of Class A Common Stock and
72,226,500 shares of Class B Common Stock outstanding. Accordingly, the current
adjusted Ownership Percentages in Section 2.1(c) of the Amendment are adjusted
to account for the change in the number of shares of Common Stock outstanding by
multiplying the Ownership Percentages set forth in the Letter by 99.39% (the
ratio of the number of shares outstanding as of March 10, 2000 over the number
of shares outstanding as of June 30, 2000).