Document:

<PAGE>   1
                                                                    Exhibit 10.8

                    ADDENDUM TO LEASE BETWEEN WALNUT BRIDGE
                      ASSOCIATES & ATX TELECOMMUNICATIONS

     On this first day of July, 1995, it is hereby agreed that all rental
payments due from ATX to Walnut Bridge Associates shall herein after be made
directly to University City Housing Associates (UCHA) and the proceeds of all
such payments shall be applied to reduction of principal loans owed on behalf of
Walnut Bridge Associates to UCHA. ATX is hereby instructed to make its rental
payments as per this addendum. It is further agreed that all other terms of the
lease dated January 2, 1993 excepting only the party to received the rental
payment are to remain in full force and effect.

<TABLE>
<CAPTION>
<S>                                                      <C>

/s/            MICHAEL KARP                                 /s/            MICHAEL KARP
------------------------------------------------------      ------------------------------------------------------
Michael Karp, General Partner of WBA                               Michael Karp, General Partner of UCHA

</TABLE>

                                       22<PAGE>   1
                                                                    Exhibit 10.9

            ADDENDUM TO LEASE BETWEEN WALNUT BRIDGE ASSOCIATES & ATX
                    TELECOMMUNICATIONS DATED JANUARY 1, 1994

     This addendum dated November 1, 1999 does hereby increase the space leased
to ATX as follows:

     Effective November 1, 1999, ATX will add to its existing lease an
additional 2,500 square feet of telecommunications space on the fourth floor and
10,000 square feet of office space on the 6th floor.

     It is hereby agreed between the parties that this additional space on the
fourth floor shall be added to the current lease at the same rate and terms and
conditions, as stated on page two, such that the lease for this additional space
shall terminate December 31, 2002 and have the same renewal option as provided
in said lease.

     It is hereby agreed between the parties that this additional space on the
sixth floor shall be added to the current lease as follows:

<TABLE>
    <S>  <C>                  <C>
    g.   Space Location.      Sixth floor, entire floor.
    h.   Footage.             10,000 (ten thousand) square feet.
    i.   Lease Term.          November 1, 1999 to December 31, 2002.
    j.   Rent Inception.      November 1, 1999
    k.   Yearly Rental.       For the first fourteen months the rent shall be
                              $12.00 per square foot due to work in progress.
    l.   Subsequent Years.    Beginning January 1, 2001 to December 31, 2001,
                              rent shall be $12.50 per square foot. Beginning
                              January 1, 2002 to December 31, 2002 rent shall be
                              $13.00 per square foot.
    m.   Usage Restrictions.  Can use for office and telemarketing purposes.
    n.   Additional Rent.     If the space is used for any telecommunications or
                              related equipment, the rent shall be the same as
                              the rent specified in the lease for the space on
                              the fifth floor of the building.
</TABLE>

     The new total leased space shall be 16,000 plus 12,500 or 28,500 square
feet and the new yearly rental as of November 1, 1999 shall be $377,950.

<TABLE>
<CAPTION>
<S>                                                  <C>

/s/                     MICHAEL KARP                   /s/                       WITNESS
----------------------------------------------         ----------------------------------------------
                    Walnut Bridge Associates                                       Witness
                        General Partner

/s/                     MICHAEL KARP                   /s/                       WITNESS
----------------------------------------------         ----------------------------------------------
                     ATX Telecommunications                                      Witness
                    General Partner and CEO

</TABLE>

                                       23<PAGE>   1
                                                                   Exhibit 10.10

            ADDENDUM TO LEASE BETWEEN WALNUT BRIDGE ASSOCIATES & ATX
                    TELECOMMUNICATIONS DATED JANUARY 1, 1994

     This addendum dated March 1, 2000 does hereby increase the space leased to
ATX as follows:

     Effective March 1, 2000, ATX will add to its existing lease an additional
2,500 square feet of telecommunications space on the fourth floor.

     It is hereby agreed between the parties that this additional space on the
fourth floor shall be added to the current lease as follows:

<TABLE>
    <S>  <C>                  <C>
    a.   Space Location.      Fourth floor.
    b.   Footage.             2,500 (two thousand and five hundred) square feet.
    c.   Lease Term.          March 1, 2000 to December 31, 2002.
    d.   Rent Inception.      March 1, 2000
    e.   Yearly Rental.       Shall be the rent specified in the lease for the
                              space on the fifth floor, as stated on page three
                              of the lease. As of March 1, 2000 the rent per
                              square foot shall be $19.55.
    f.   Usage Restrictions.  Any telecommunications or related equipment.
    g.   Additional Rent.     If the remaining 7,500 (seven thousand five
                              hundred) square feet of space on the fourth floor
                              is used for any telecommunications or related
                              equipment, the rent shall be the same as specified
                              herewithin.
</TABLE>

     The new total leased space shall be 28,500 plus 2,500 or 31,000 square feet
and the new yearly rental as of March 1, 2000 shall be $437,525 (or $36,450.42
per month).

<TABLE>
<CAPTION>
<S>                                                  <C>

/s/                     MICHAEL KARP                   /s/                       WITNESS
----------------------------------------------         ----------------------------------------------
                    Walnut Bridge Associates                                       Witness
                        General Partner

/s/                     MICHAEL KARP                   /s/                       WITNESS
----------------------------------------------         ----------------------------------------------
                     ATX Telecommunications                                      Witness
                    General Partner and CEO

</TABLE>

                                       24<PAGE>   1
                                                                   Exhibit 10.11

CoreStates

PHILADELPHIA NATIONAL BANK, INCORPORATED AS CORESTATES BANK, N.A.

<TABLE>
<CAPTION>
                                                            LETTER OF CREDIT
OUR CREDIT NO.         ISSUE DATE       EXPIRY DATE              AMOUNT
--------------         -----------      -----------      -----------------------
<S>                    <C>              <C>              <C>
512671P                30-JUL-1993      30-JUL-1994          USD130,000.00
</TABLE>

<TABLE>
<CAPTION>
BENEFICIARY                                                            APPLICANT
-----------                                                            ---------
<S>                                                      <C>
GULF INSURANCE COMPANY                                   MICHAEL A. KARP TRADING AS ATX
C/O AAA BOND/PROS INC.                                     TELECOMMUNICATIONS SERVICES
ONE DUPONT STREET                                        1062 LANCASTER AVENUE, SUITE 617
PLAINVIEW, NEW YORK 11803                                ROSEMONT, PA 19010
</TABLE>

DEAR BENEFICIARY:

     WE HAVE ESTABLISHED THIS IRREVOCABLE LETTER OF CREDIT IN YOUR FAVOR AS
BENEFICIARY FOR DRAWINGS UP TO USD130,000.00 (ONE HUNDRED THIRTY THOUSAND AND
00/100 U.S. DOLLARS) EFFECTIVE IMMEDIATELY. THIS LETTER OF CREDIT IS ISSUED,
PRESENTABLE AND PAYABLE AT OUR OFFICE AT P.O. BOX 13866, 530 WALNUT STREET,
LETTER OF CREDIT DEPARTMENT, SEVENTH FLOOR, FIND CODE 1-9-7-1, PHILADELPHIA, PA
19106 AND EXPIRES WITH OUR CLOSE OF BUSINESS ON 30-JUL-1994.

     THE TERM "BENEFICIARY" INCLUDES ANY SUCCESSOR BY OPERATION OF LAW OF THE
NAMED BENEFICIARY INCLUDING WITHOUT LIMITATION ANY LIQUIDATOR, REHABILITATOR,
RECEIVER OR CONSERVATOR.

     WE HEREBY UNDERTAKE TO DULY HONOR YOUR SIGHT DRAFT(S) DRAWN ON US,
INDICATING OUR CREDIT NO. 512671, FOR ALL OR ANY PART OF THIS CREDIT UPON
PRESENTATION OF YOUR DRAFT DRAWN ON US AT OUR OFFICE SPECIFIED IN PARAGRAPH ONE
(1) ON OR BEFORE THE EXPIRATION DATE HEREOF OR ANY AUTOMATICALLY EXTENDED EXPIRY
DATE.

     EXCEPT AS EXPRESSLY STATED HEREIN, THIS UNDERTAKING IS NOT SUBJECT TO ANY
AGREEMENT, REQUIREMENT OR QUALIFICATION. THE OBLIGATION OF PHILADELPHIA NATIONAL
BANK, INCORPORATED AS CORESTATES BANK N.A. UNDER THIS LETTER OF CREDIT IS THE
INDIVIDUAL OBLIGATION OF PHILADELPHIA NATIONAL BANK, INCORPORATED AS CORESTATES
BANK N.A. AND IS IN NO WAY CONTINGENT UPON REIMBURSEMENT WITH RESPECT THERETO.

     THIS LETTER OF CREDIT IS DEEMED TO BE AUTOMATICALLY EXTENDED WITHOUT
AMENDMENT FOR ONE (1) YEAR FROM THE EXPIRATION DATE OR ANY FUTURE EXPIRATION
DATE, UNLESS AT
<PAGE>   2

LEAST THIRTY (30) DAYS PRIOR TO SUCH EXPIRATION DATE, WE NOTIFY YOU BY CERTIFIED
MAIL THAT THIS LETTER OF CREDIT WILL NOT BE EXTENDED FOR ANY SUCH ADDITIONAL
PERIOD.

     THIS LETTER OF CREDIT IS SUBJECT TO AND GOVERNED BY THE LAWS OF THE STATE
OF NEW YORK AND THE 1983 REVISION OF THE UNIFORM CUSTOMS AND PRACTICE FOR
DOCUMENTARY CREDITS OF THE INTERNATIONAL CHAMBER OF COMMERCE (PUBLICATION NO.
406) AND IN THE EVENT OF ANY CONFLICT THE LAWS OF NEW YORK WILL CONTROL. IF THIS
CREDIT EXPIRES DURING AN INTERRUPTION OF BUSINESS AS DESCRIBED IN ARTICLE 19 OF
SAID PUBLICATION 400. THE BANK HEREBY SPECIFICALLY AGREES TO EFFECT PAYMENT IF
THIS CREDIT IS DRAWN AGAINST WITHIN THIRTY (30) DAYS AFTER THE RESUMPTION OF
BUSINESS.

     ALL INQUIRIES REGARDING THIS CREDIT SHOULD BE DIRECTED TO US AT OUR PHONE
NUMBERS (215) 973-3520; (215) 973-5981; (215) 973-8157; (215) 973-1944.

                                          /s/ AUTHORIZED SIGNATURE
                                          --------------------------------------
                                          AUTHORIZED SIGNATURE
<PAGE>   3

CoreStates CORESTATES BANK, N.A.

<TABLE>
<S>                                           <C>
OUR CREDIT NO.                                DATE
512671P                                       September 3, 1997
BENEFICIARY                                   APPLICANT
GULF INSURANCE COMPANY                        MICHAEL A. KARP TRADING AS
C/O AAA BOND/PROS INC                         ATX TELECOMMUNICATIONS SERVICES
ONE DUPONT STREET                             1062 LANCASTER AVENUE, SUITE 617
PLAINVIEW, NEW YORK 11803                     ROSEMONT, PA 19010
</TABLE>

DEAR BENEFICIARY:

     WE HEREBY AMEND OUR IRREVOCABLE STANDBY LETTER OF CREDIT AS FOLLOWS:

     1) THE AMOUNT AVAILABLE IS INCREASED BY: USD49,786.50 FOR A NEW AVAILABLE
BALANCE OF: USD179,786.50

     EXCEPT SO FAR AS OTHERWISE EXPRESSLY STATED HEREIN THIS AMENDMENT AND THE
ORIGINAL LETTER OF CREDIT ARE NOW SUBJECT TO THE "UNIFORM CUSTOMS AND PRACTICE
FOR DOCUMENTARY CREDITS: (1993 REVISION), INTERNATIONAL CHAMBER OF COMMERCE,
PUBLICATION No. 500".

     ALL OTHER TERMS AND CONDITIONS REMAIN UNCHANGED.

     ALL INQUIRIES REGARDING THIS CREDIT SHOULD BE DIRECTED TO US AT OUR PHONE
NUMBERS (215) 973-5981; (215) 973-8157; (215) 973-1944.

                                          /s/ AUTHORIZED SIGNATURE
                                          --------------------------------------
                                          AUTHORIZED SIGNATURE

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