Document:

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                                                                   Exhibit 10.6C

                                 PROMISSORY NOTE

$300,000.00                                                     January 13, 2000

         FOR VALUE RECEIVED, the undersigned hereby promises to pay to Verilink
Corporation ("Verilink") at Huntsville, Alabama, the principal amount of Three
Hundred Thousand Dollars ($300,000.00). All principal due under this Note shall
be paid on the earlier of (i) termination of the undersigned's employment by
Verilink for any reason provided, however that for purposes of this paragraph
(i), the principal balance of this Note will be reduced by 25% each full year
that the undersigned remains employed by Verilink; or (ii) within one (1) year
after the value of the undersigned's exercisable Verilink stock options exceed
$2,000,000 (fair market value of stock subject to exercisable options less total
exercise price of such options). Interest shall be forgiven.

         This Note may be prepaid at any time, in whole or in part, without
premium or penalty.

         If action should be instituted on this Note, the undersigned agrees to
pay the holder, in addition to such amounts owed pursuant to this Note, all
costs of collection, including a reasonable sum of attorney's fees.

         This Promissory Note shall be governed by the laws of the State of
Alabama.

                                               /s/ Graham G. Pattison
                                        -----------------------------------
                                                 Graham G. Pattison<PAGE>   1
                                                                   Exhibit 10.7A

                                 PROMISSORY NOTE

$300,000.00                                                     December 1, 1999

         FOR VALUE RECEIVED, the undersigned hereby promises to pay to Verilink
Corporation ("Verilink") at Huntsville, Alabama, the principal amount of Three
Hundred Thousand Dollars ($300,000.00). All principal due under this Note shall
be paid on the earlier of (i) termination of the undersigned's employment with
Verilink for any reason provided, however, that for purposes of this paragraph
(i), the principal balance of this Note will be reduced by 50% for each full
year that the undersigned remains employed by Verilink; or (ii) within one (1)
year after the value of the undersigned's exercisable Verilink stock options
exceed $2,000,000 (fair market value of stock subject to exercisable options
less total exercise price of such options). Interest shall be forgiven.

         This Note may be prepaid at any time, in whole or in part, without
premium or penalty.

         If action should be instituted on this Note, the undersigned agrees to
pay the holder, in addition to such amounts owed pursuant to this Note, all
costs of collection, including a reasonable sum of attorney's fees.

         This Promissory Note shall be governed by the laws of the State of
Alabama.

                                                 /s/ Michael L. Reiff
                                             ------------------------------
                                                   Michael L. Reiff<PAGE>   1
                                                                   Exhibit 10.7B

                            NOTE SECURED BY MORTGAGE

DATE: Effective December 18, 2000

MAKER: Mike Reiff

PAYEE: Verilink Corporation

PLACE FOR PAYMENT: 127 Jetplex Circle, Madison, AL 35758

PRINCIPAL AMOUNT: Four Hundred Nine Thousand Eight Hundred Thirty-Six and
                  23/100 Dollars ($409,836.23)

ANNUAL INTEREST RATE ON UNPAID
PRINCIPAL: The Interest Rate on this Promissory Note shall be 0%.

TERMS OF PAYMENT:

         A. Maker shall repay the principal of the note before December 18,
2007.

         B. If Maker sells the property securing this Note for less than
$409,836.23, after deducting costs of sale, the principal balance of this Note
shall be reduced by such amount.

SECURITY FOR PAYMENT:

         A. Date: December 18, 2000

         B. Debtor: Mike Reiff

         C. Secured Party: Payee herein;

         D. County Where Collateral located: Madison County, Alabama;

         E. Collateral: See Legal Description attached as Exhibit "A"

         Maker promises to pay to the order of Payee at the place for payment
and according to the terms of payment the principal amount stated above. All
unpaid amounts shall be due by the maturity date.

         On default in the payment of this Note or in the performance of any
obligation in any instrument securing or collateral to it, this Note and all
obligations in all instruments securing or collateral to it shall become
immediately due at the election of Payee. Maker and each surety, endorser, and
guarantor waive all exemptions to the

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extent permitted by law, diligence in collection, demands for payment,
presentations for payment, notices of intention to accelerate maturity, notice
of acceleration, protest, notice of protest, and all other notices.

         If this Note or any instrument securing or collateral to it is given to
an attorney for collection or enforcement, or if suit is brought for collection
or enforcement, or if it is collected or enforced through probate, bankruptcy,
or other judicial proceeding, then Maker shall pay Payee reasonable attorney's
fees in addition to other amounts due.

         Nothing in this Note shall authorize the collection of interest in
excess of the highest rate allowed by law.

         Each Maker is responsible for the entire amount of the Note.

         The terms Maker and Payee and other nouns and pronouns include the
plural if more than one. The terms Maker and Payee also include their respective
heirs, personal representatives, and assigns.

         Maker agrees to pay all costs incurred in recording the mortgage
hereinabove described. In the event Payee pays such amount, said amount shall be
added to the principal of this Note.

                                                /s/ Mike Reiff
                                            ------------------------
                                                Mike Reiff

                                      -2-<PAGE>   1
                                                                  Exhibit 10.24A

                               FIRST AMENDMENT TO
                     PREMISES LICENSE AND SERVICE AGREEMENT

         THIS FIRST AMENDMENT to the Premises License and Service Agreement is
made and entered into this 12th day of July 2001, among Trustees of Boston
University (the "University"), Beacon Telco, L.P. ("Telco") and Verilink, Inc.
(the "Company").

         WHEREAS, the University, Telco and the Company are parties to the
Premises License and Services Agreement, dated October 16, 2000 (the
"Agreement");

         WHEREAS, the Company issued and delivered Warrants and Bonus Payments
to Telco, pursuant to the terms and conditions of the Cooperative Research
Agreement dated October 16, 2000 (for purposes of the first Bonus Payment) and a
separate Warrant and Stockholders Agreement dated October 16, 2000 between the
Company and Telco in partial consideration for the license to access certain
services and premises of the University;

         WHEREAS, it was the understanding that the Company would be given
access to additional premises of the University, subject to the University's
discretion, as its research and development project activities grew and that
Telco would provide additional consideration to the University pursuant to their
previous agreements; and

         WHEREAS, the parties wish to amend certain provisions of the Agreement
to reflect the additional access to the University's premises being granted to
the Company.

         NOW, THEREFORE, in consideration of their mutual promises and for other
good and valuable consideration, the receipt and sufficiency of which is hereby
acknowledged, the parties, pursuant to the section 14.04 of the Agreement,
hereby amend the Agreement as follows:

1.       Article I, Certain Definitions.

         The following term in Section 1.01 Defined Terms shall be amended to
         read ad follows:

                  "LICENSED PREMISES" means as applied to Company (a)
         approximately 3400 square feet of office space on the sixth (6th) Floor
         of the Building, which shall initially be Rooms 611, 613, 614 and 620,
         and (b) shared access to, on a basis reasonably equivalent to other
         users thereof as determined solely by the University in its good faith
         discretion, (i) the Optics Laboratory 615 on the sixth (6th) Floor of
         the Building; and (ii) other laboratories in the Building, and the
         equipment therein. Access to these other laboratories will be
         coordinated through the University in its sole good faith discretion.

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2.       Except as specifically amended hereby, the Agreement remains in full
force and effect.

         IN WITNESS WHEREOF, the parties hereto have caused this First Amendment
to be signed as of the date first above written.

VERILINK CORPORATION                         TRUSTEES OF BOSTON UNIVERSITY

By:      /s/ Graham Pattison                 By:      /s/ Martin J. Howard
  ----------------------------------            --------------------------------
Name:    Graham Pattison                     Name:    Martin J. Howard
     -------------------------------              ------------------------------
Title:      CEO of Verilink                  Title:   Assistant Treasurer
      ------------------------------               -----------------------------

BEACON TELCO, L.P.

By Beacon Photonics, Inc.
     Its General Partner

By:  /s/ Alok Prasad
   ---------------------------------
     Alok Prasad, President

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