Document:

<PAGE>   1

                                                                 EXHIBIT 10.19.1

                                 AMENDMENT NO. 1

THIS AMENDMENT ("Amendment") is made and entered into effective this 12th day of
March, 1998; by and between WILLIAMS COMMUNICATIONS, INC. D/B/A WILLIAMS NETWORK
SERVICES ("Seller") and UNIVERSAL ACCESS, INC. ("Customer").

WHEREAS, Seller and Customer are parties to that certain Carrier Services
Agreement, Contract No. 98R0613.00 which is dated June 29, 1998, (the
"Agreement"); and

WHEREAS, Seller and Customer desire to amend the Agreement; and

NOW, THEREFORE in consideration of the foregoing premises and mutual promises
and covenants of the parties hereto, the receipt and sufficiency of which is
hereby acknowledged, Seller and Customer agree to amend the Agreement as
follows:

1.       Section 3.2 of the Agreement shall be amended to read as follows:

"The duration of this Agreement shall continue for a term of six (6) years (the
"Initial Term") from the Effective Date. This Agreement shall thereafter
automatically renew for successive one-year periods (each, a "Renewal Term")
unless canceled by either party by giving written notice of such cancellation
not less than sixty (60) days before the end of the Initial Term, or any Renewal
Term. Unless Customer is in default, any Service being provided at the time of
termination shall continue until the natural end of such Service as specified in
the applicable Service Order upon the terms and conditions of this Agreement;
provided that Customer may not order any new Service without first renewing this
Agreement. The charges for Services or Ancillary Services during any such
extension shall be the then current Seller charges."

2.       Section 3.3 of the Agreement shall be amended to read as follows:

"Commencing twelve (12) months after the calendar month including the Effective
Date, Customer shall be obligated to purchase on-network interexchange Services
under this Agreement in the amount of five hundred thousand dollars ($500,000)
per month (the "Revenue Commitment"). All charges for Services in this Agreement
shall be determined in accordance with the pricing set forth in the Service
Schedules attached hereto or on Customer's Service Orders, as applicable. In
determining whether the monthly charges are of a sufficient dollar amount to
meet Customer's Revenue Commitment, Seller will include any discounts applicable
to Customer but will not include any credits to which Customer may be entitled,
late payment penalties, taxes and other government imposed surcharges, or
payments made by Customer to reimburse Seller for third party costs paid to
unaffiliated entities, including, but not limited to, local access charges,
taxes, installation charges, off-network charges, one-time fees and other
similar costs. To the extent that, in any month during the Initial Term hereof,
Customer fails to have signed Service Orders or a total aggregate billing of
applicable Services from Seller greater than or equal to the Revenue Commitment
amount, Seller shall invoice Customer on Customer's next invoice, an amount
equal to the difference between the Revenue Commitment amount and the amount of
Services actually purchased or committed to by Service Order by Customer. For
purposes of this Agreement, "on-network" or "on-net" shall mean interexchange
service provided by Seller on facilities owned by Seller and bounded by Seller
points of presence or Services that are ordered and scheduled to be on Seller
owned facilities within a one year period from the date of order (i.e. Customer
will receive On-Net pricing at the time of the Service Order provided that the
Seller has indicated that the route will be On-Net within twelve (12) months of
the Service Order). At the time that any off-net circuit is available for on-net
use, Customer agrees to convert circuit to on-net facilities at the first
mutually acceptable date and time."

<PAGE>   2

3.       Section 2.1 of the Private Line Service Schedule which is a part of the
Agreement shall be amended to read as follows:

         "2.1 IXC. DS-3, OC-3 and OC-12 On-Net Private Line Services shall be
         provided at the following rates:

                DS-3:  [***]  per DS-0 V & H mile per month
                OC-3:  [***]  per DS-0 V & H mile per month
                OC-12: [***]  per DS-0 V & H mile per month

         Notwithstanding the foregoing, the minimum monthly charges for Private
Line Service shall be as follows:

<TABLE>
                             Minimum Monthly Charges
<S>                                           <C>
                           DS-3                [***]
                           OC-3                [***]
                           OC-12               [***]
                           OC-48               [***]
</TABLE>

         All other IXC rates will be determined on an individual case basis and
         will be set forth on the Service Order."

4.       Customer shall begin receiving the pricing set forth in this Amendment
beginning on Customer's December 1, 1998 invoice and shall receive such pricing
for the remainder of the Term of the Agreement. Customer's pending and existing
Services shall receive the pricing set forth in this Amendment on a going
forward basis only and shall not receive any credit for Services which have been
billed prior to Customer's December 1, 1998 invoice.

5.       Except as specifically amended herein, all terms, conditions and
provisions contained in the Contract shall remain unchanged and in full force
and effect.

IN WITNESS WHEREOF, the parties have executed this Amendment on the day and year
first above set forth.

WILLIAMS COMMUNICATIONS, INC.                     UNIVERSAL ACCESS, INC.

/s/ RON HARDEN                                    /s/ ROBERT POMMER
(SIGNATURE)                                       (SIGNATURE)

Ron Harden                                        Robert Pommer
----------------------------                      ----------------------------
(PRINT)                                           (PRINT)

V.P. Sales & Marketing                            Chief Operating Officer
----------------------------                      ----------------------------
(TITLE)                                           (TITLE)

<PAGE>   3

                                                        WILLIAMS
                                                        COMMUNICATIONS
                                                        One Williams Center
                                                        Tulsa, Oklahoma 74172
                                                        918/573-2000

April 15, 1999

Mr. Robert J. Pommer
Universal Access, Inc.
1021 Adams Street, Suite 101
Chicago, IL 60607

Reference:   Amendment No. 1 to the Carrier Services Agreement
             date June 29, 1998 Williams Agreement 98R0613.00

Dear Mr. Pommer:

Please find enclosed for your files a fully executed original of the above
referenced Amendment No. 1 to that certain Carrier Services Agreement between
Universal Access and Williams.

If you should have any questions or if this office may be of future assistance,
please contact me at 918-573-2123.

Sincerely,

Debra Stockton
Contract Administration

Enclosure<PAGE>   1
                                                                 EXHIBIT 10.19.2

                                 AMENDMENT NO. 2

THIS AMENDMENT ("Amendment") is made and entered into effective this 1st day of
July, 1999, by and between WILLIAMS COMMUNICATIONS, INC. D/B/A WILLIAMS NETWORK
SERVICES ("Seller") and UNIVERSAL ACCESS, INC. ("Customer").

WHEREAS, Seller and Customer are parties to that certain Carrier Services
Agreement, Contract No. 98R0613.00 which is dated June 29, 1998 as amended by
Amendment No. 1 dated March 12, 1999, (together the "Agreement"); and

WHEREAS, Seller and Customer desire to amend the Agreement; and

NOW, THEREFORE in consideration of the foregoing premises and mutual promises
and covenants of the parties hereto, the receipt and sufficiency of which is
hereby acknowledged, Seller and Customer agree to amend the Agreement as
follows:

1.       Section 3.2 of the Agreement shall be amended to read as follows:

"The duration of this Agreement shall continue for a term of ten (10) years (the
"Initial Term") from the Effective Date. This Agreement shall thereafter
automatically renew for successive one-year periods (each, a "Renewal Term")
unless canceled by either party by giving written notice of such cancellation
not less than sixty (60) days before the end of the Initial Term, or any Renewal
Term. Unless Customer is in default at the end of any applicable cure period,
any Service being provided at the time of cancellation shall continue until the
end of such Service as specified in the applicable Service Order upon the terms
and conditions of this Agreement; provided that Customer may not order any new
Service without first renewing this Agreement. The charges for Services or
Ancillary Services during any such extension shall be the then current Seller
charges."

2.       Section 2.1 of the Private Line Service Schedule which is a part of the
Agreement shall be amended to read as follows:

         "2.1 IXC. DS-1, DS-3, OC-3 and OC-12 and OC-48 On-Net Private Line
         Services shall be provided at the following rates:

               DS-1:  [***] per DS-0 V & H mile per month
               DS-3:  [***] per DS-0 V & H mile per month
               OC-3:  [***] per DS-0 V & H mile per month
               OC-12: [***] per DS-0 V & H mile per month
               OC-48: [***] per DS-0 V & H mile per month

         Notwithstanding the foregoing, the minimum monthly charges for Private
Line Service shall be as follows:

*** Certain information on this page has been omitted and filed separately with
the Commission. Confidential treatment has been requested with respect to the
omitted portions.

                                        1

<PAGE>   2

<TABLE>
<CAPTION>
                             Minimum Monthly Charges
<S>                                           <C>
                           DS-1                [***]
                           DS-3                [***]
                           OC-3                [***]
                           OC-12               [***]
                           OC-48               [***]
</TABLE>

         All other IXC rates will be determined on an individual case basis and
         will be set forth on the Service Order."

2.       The pricing set fourth in Section 2 of this Amendment shall not apply
to any existing Services being purchased by Customer (except as set forth in
paragraph 3 of this Amendment) and shall only apply to and be reflected on new
Service Orders placed by Customer after July 1, 1999. The above rates for new
Service Orders placed by Customer after July 1, 1999 shall be reflected on
Customer's July 1, 1999 invoice and Customer shall receive such pricing for any
new Service Orders placed during the remainder of the Term of the Agreement.

3.       Customer's Services ordered prior to July 1, 1999 (hereinafter
"Existing Services") shall be re-priced based on the pricing set forth in
Section 2 of this Amendment going forward after July 1, 1999, on a revenue
basis until Customer has achieved a total of [***] of new monthly recurring
revenue with Seller. Such re-pricing shall occur as follows: for every new
dollar of revenue that Customer generates with Seller after July 1, 1999,
Seller shall re-price a corresponding amount of Existing Services beginning
with Customer's most recently ordered circuits. (For example, if Customer
generates $10,000 of new business, Seller will re-price $10,000 of Existing
Services.) Customer shall receive such re-pricing of Existing Services the
month following the month in which the new Service Order was placed by Customer.

4.       Upon placement of a total of $[***] of new Service Orders by Customer
after July 1, 1999, all of Customer's Existing Services shall be re-priced at
the rates set forth in Section 2.1 of this Amendment No. 2. Customer shall
receive such re-pricing of all Existing Services the month following the month
in which the total of $[***] of new Service Orders are placed by Customer.

5.       Except as specifically amended herein, all terms, conditions and
provisions contained in the Agreement shall remain unchanged and in full force
and effect.

IN WITNESS WHEREOF, the parties have executed this Amendment on the day and year
first above set forth.

WILLIAMS COMMUNICATIONS, INC.             UNIVERSAL ACCESS, INC.
 /s/   GORDON MARTIN
---------------------------------------    /s/ ROBERT J. POMMER
         (SIGNATURE)                      (SIGNATURE)
        Gordon Martin
---------------------------------------   /s/ ROBERT J. POMMER
         (PRINT)                          (PRINT)
Senior Vice President, Network Services
---------------------------------------   /s/ Chief Operating Officer
         (TITLE)                          (TITLE)

*** Certain information on this page has been omitted and filed separately with
the Commission. Confidential treatment has been requested with respect to the
omitted portions.

                                        2

Source: [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00003-of-00352.parquet"}, [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00003-of-00352.parquet"}]]