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                                                                     EXHIBIT 2.3


                                October 20, 1999



ICM Communications Integration, Inc.
4122 128th Avenue, S.E., Suite 300
Bellevue, Washington  98006
Attn:  Dennis Schillinger


The Persons on Attached Schedule I


                  Re: Agreement and Plan of Merger dated August 13, 1999

Dear Ladies and Gentlemen:

                  This letter agreement serves as an amendment to the Agreement
and Plan of Merger dated as of August 13, 1999 (the "Agreement") by and among
PentaStar Communications, Inc., OC Mergerco 2, Inc., ICM Communications
Integration, Inc. and the Shareholders of ICM Communications Integration, Inc.
All capitalized terms used in this letter agreement without definition have the
respective meanings given to them in the Agreement.

                  The parties hereby amend the Agreement as follows:

                  1. The Closing shall occur at 8:00 a.m. Denver, Colorado time
on Monday, October 25, 1999, the proposed date on which PentaStar's Registration
Statement will be declared effective by the SEC. At the Closing, PentaStar will
deliver a promissory note in the form attached as Exhibit A (the "Temporary
Note") in an amount determined pursuant to clause (a) of Section 2(k) of the
Agreement (the "Cash Purchase Price Amount"), rather than delivering cash in
such amount at the Closing. Upon closing of the IPO, cash in an amount equal to
the Cash Purchase Price Amount will be delivered as specified in Section 2(k) of
the Agreement in exchange for the return of the Temporary Note to PentaStar and
its cancellation. All other Closing conditions set forth in Sections 6.1 and 6.2
of the Agreement shall be completed at the Closing as set forth in such
Sections. If the closing of the IPO does not occur by the close of business on
October 29, 1999, the Closing shall be unwound and rescinded effective as of
8:00 a.m. Denver, Colorado time on Monday, October 25, 1999 as if it had never
occurred, and the Agreement will remain in full force and effect until
terminated in accordance with its terms. In order to facilitate such unwinding
and rescission if necessary, the Company will not be merged into the Acquiror
until cash in an amount equal to the Cash Purchase Price Amount is delivered as
specified in Section 2(k) of the Agreement.

                  2. (a) The definition of "Cash" set forth in Exhibit 1.1(a) is
amended and restated to read in its entirety as follows:


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                    Cash means the sum of (a) the amount of cash and cash
                    equivalents held by the Company at 11:59 p.m. Pacific
                    Standard Time ("PST") on October 19, 1999 which continues to
                    be held by the Company on the Closing Date plus (b) the
                    amount of cash received by the Company in respect of the
                    August/September Receivables between 12:00 a.m. PST on
                    October 20, 1999 and the Closing Date which continues to be
                    held by the Company on the Closing Date. "Cash" for purposes
                    of this Agreement, including, without limitation, for
                    purposes of calculating Cash held by the Company to
                    determine the amount of Cash to be set forth on the
                    Estimated Closing Date Balance Sheet or on the Closing Date
                    Balance Sheet pursuant to Section 2 or for making any other
                    calculation or determination pursuant to Section 2 or any
                    other section of the Agreement, shall not include any other
                    cash or cash equivalents ("Other Cash") which are acquired
                    by the Company between 12:00 a.m. PST on October 20, 1999
                    and the Closing Date. Such Other Cash shall be separately
                    set aside by the Company until the Closing Date and shall be
                    the property of PentaStar upon the Closing Date.

                    (b) A definition of "August/September Receivables" is added
to Exhibit 1.1(a) to read in its entirety as follows:

                    August/September Receivables means commissions received by
                    the Company prior to the Closing Date or by the Acquiror on
                    or after the Closing Date pursuant to the US West Contract
                    in respect of, and only in respect of, (a) customer's orders
                    that were submitted to and accepted by US West in August or
                    September 1999 or (b) customer installations completed by US
                    West in August or September 1999, but in either case net of
                    the amount of any related Cash Covered Accrued Commission
                    Liability.

                    (c) The definition of "Payment Period" set forth in Exhibit
1.1(a) is deleted.

                    (d) If, after the Closing Date, the Acquiror receives
payment from US West in respect of an August/September Receivable, the Acquiror
will immediately deliver the

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amount of such August/September Receivable, netted as set forth in the
definition thereof, to the Shareholders in the same proportions that the Cash
Purchase Price Amount is paid to them pursuant to Section 2(k) of the Agreement.

                    (e) During the 180 day period following the Closing Date, no
Shareholder will, and no Shareholder will permit such Shareholder's agents or
attorneys to, contact US West concerning the Closing Accounts Receivable.

                    (f) If the closing of the IPO does not occur by the close of
business on October 29, 1999, Section 2 of this letter agreement shall be of no
further force and effect and the changes to the Agreement described in this
Section 2 shall be void ab initio.

                  3. Notwithstanding the definition of "Retained Liabilities,"
the amount of the Retained Liability to the Acquiror in respect of the Simple
IRA Plan is $14,634.67 if the closing of the IPO occurs on or before October 31,
1999. If the closing of the IPO occurs after that date, the amount of such
Retained Liability would be the amount accrued in respect thereof in the
ordinary course of business consistent with the 1999 accruals for such
liability.

                  4. Section 3.1(j) of the Agreement is amended and restated in
its entirety to read as follows:

                    (j) Notes and Accounts Receivable. The $1,267,000.00 net
                    amount of the notes and accounts receivable of the Company
                    reflected on its Latest Balance Sheet, and all notes and
                    accounts receivable arising on or prior to the Closing Date,
                    arose and will arise from bona fide transactions by the
                    Company in the ordinary course of business and will be paid
                    to PentaStar as set forth in Section 5.8.

                  5. Exhibit 1.1 (c) is amended and restated in its entirety by
Exhibit 1.1(c) attached hereto.

                  6. Exhibit 1.1 (d) is amended and restated in its entirety by
Exhibit 1.1(d) attached hereto.

                  7. Exhibit 3.1(b)(ii) is amended and restated in its entirety
by Exhibit 3.1(b)(ii) attached hereto.

                  8. Exhibit 3.1(c) is amended and restated in its entirety by
Exhibit 3.1(c) attached hereto.

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                  9. Exhibit 3.1(e)(iv) is amended and restated in its entirety
by Exhibit 3.1(e)(iv) attached hereto.

                  10. Exhibit 3.1(e)(vi) is amended and restated in its entirety
by Exhibit 3.1(e)(vi) attached hereto.

                  11. Exhibit 3.1(g)(i) is amended and restated in its entirety
by Exhibit 3.1(g)(i) attached hereto.

                  12. Exhibit 3.1(h) is amended and restated in its entirety by
Exhibit 3.1(h) attached hereto.

                  13. Exhibit 3.1(k) is amended and restated in its entirety by
Exhibit 3.1(k) attached hereto.

                  14. Exhibit 3.1(m)(i) is amended and restated in its entirety
by Exhibit 3.1(m)(i) attached hereto.

                  15. Exhibit 3.1(m)(iii) is amended and restated in its
entirety by Exhibit 3.1(m)(iii) attached hereto.

                  16. Exhibit 3.1(s) is amended and restated in its entirety by
Exhibit 3.1(s) attached hereto.

                  17. Exhibit 3.1(t) is amended and restated in its entirety by
Exhibit 3.1(t) attached hereto.

                  18. Exhibit 3.3(a)(ii) is amended and restated in its entirety
by Exhibit 3.3(a)(ii) attached hereto.

                  19. Exhibit 3.3(a)(x) is amended and restated in its entirety
by Exhibit 3.3(a)(x) attached hereto.

                  20. Exhibit 4.8 is amended and restated in its entirety by
Exhibit 4.8 attached hereto.


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                  By signing below, you acknowledge and agree that (a) this
letter agreement amends the Agreement as set forth above, (b) in the event of
any conflict between this letter agreement and the Agreement, this letter
agreement shall control, and (c) the Agreement, as amended by this letter
agreement, remains in full force and effect.

                                            Very truly yours,

                                            PENTASTAR COMMUNICATIONS, INC.


                                            By:        /s/ Craig J. Zoellner
                                               --------------------------------
                                            Name:      Craig J. Zoellner
                                            Title:     President


                                            OC MERGERCO 1, INC.


                                            By:        /s/ Craig J. Zoellner
                                               --------------------------------
                                            Name:      Craig J. Zoellner
                                            Title:     President

         Agreed and accepted this 20th day of October, 1999, effective as of
August 13, 1999.


                                            ICM COMMUNICATIONS INTEGRATION, INC.


                                            By:        /s/ Dennis Schillinger
                                               --------------------------------
                                            Name:      Dennis Schillinger
                                            Title:     President

                                            SHAREHOLDERS:



                                            /s/ Dennis Schillinger
                                            -----------------------------------
                                            Dennis Schillinger

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                                            /s/ N. van Gelder
                                            -----------------------------------
                                            Nicolas van Gelder


                                            /s/ Norma A. Douthit
                                            -----------------------------------
                                            Norma Douthit


                                            /s/ John R. Hall
                                            -----------------------------------
                                            John Hall


                                            /s/ Charles E. Gibson
                                            -----------------------------------
                                            Charles Gibson


                                            /s/ Jeannette D. Murphy
                                            -----------------------------------
                                            Jeanette Murphy


                                            /s/ R. Johnson
                                            -----------------------------------
                                            Rick Johnson


                                            /s/ Ed Peterson
                                            -----------------------------------
                                            Ed Peterson




Spouses of Shareholders (not Shareholders)



/s/ Monica Schillinger
------------------------------------------
Monica Schillinger


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/s/ Kirsten van Gelder
------------------------------------------
Kirstin van Gelder



/s/ David T. Douthit
------------------------------------------
David T. Douthit



/s/ Judy Gibson
------------------------------------------
Judy Gibson



/s/ Dennis M. Balascio
------------------------------------------
Dennis M. Baluseio



/s/ MA Johnson
------------------------------------------
Margaret Johnson



/s/ Glenda Blackburn
------------------------------------------
Glenda Blackburn



cc:   Patrick Moran, Esq.


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                                   SCHEDULE I

Dennis Schillinger
Nicolas van Gelder
Norma Douthit
John Hall
Charles Gibson
Jeanette Murphy
Rick Johnson
Ed Peterson



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