Document:

<PAGE>

                    AMENDMENT NO. 1 TO STANDBY TERM LOAN NOTE

      Reference is made to that $30,000,000.00 Standby Term Loan Note of STAR
TELECOMMUNICATIONS, INC., a Delaware corporation with its chief executive
offices located at 223 East De La Guerra, Santa Barbara, California, 93101
(together with its successors and assigns, the "Maker"), dated June 30, 2000 (as
the same may be amended, modified or supplemented from time to time, including
any extensions, refinancings, refundings or renewals thereof in whole or in
part, collectively, the "Term Note"), payable to MCI WORLDCOM NETWORK SERVICES,
INC., a Delaware corporation with offices located at 6929 N. Lakewood Avenue,
Mail Drop 5.2-510, Tulsa, Oklahoma 74117 (the "Holder"). Notwithstanding
anything contained in the Term Note to the contrary, from and after the date
hereof, unless sooner accelerated, the Term Note shall mature on or before the
earlier to occur of (such date being referred to herein as the "Maturity Date"):
(a) termination of the Agreement and Plan of Merger dated February 11, 2000, by
and between the Maker, STI Merger Co. and World Access, Inc. (the "Merger
Agreement"); (b) consummation of the merger transaction contemplated by the
Merger Agreement; or (c) August 31, 2000, without notice or presentment. Nothing
herein shall be considered or construed to be an agreement by Holder to extend
the Maturity Date beyond August 31, 2000, or to make any Advances (as defined in
the Term Note) to Maker on the Maturity Date or any date after the Maturity
Date.

      When attached to the Term Note, this Amendment No. 1 shall become a part
of the Term Note, and the terms and provisions of the Term Note as modified by
this Amendment No. 1 shall remain in full force and effect.

Dated as of: July ___, 2000

                    [SIGNATURES APPEAR ON THE FOLLOWING PAGE]

                                        1
<PAGE>

ATTEST:                                STAR TELECOMMUNICATIONS, INC.

By:                                    By:
   -------------------------------        -------------------------------
Name:                                  Name:
     -----------------------------          -----------------------------
Title:                                 Title:
      ----------------------------           ----------------------------

                                       Agreed to and Accepted By:

ATTEST:                                MCI WORLDCOM NETWORK
                                       SERVICES, INC.

By:                                    By:
   -------------------------------        -------------------------------
Name:                                  Name:
     -----------------------------          -----------------------------
Title:                                 Title:
      ----------------------------           ----------------------------

                                       2<PAGE>

                       AMENDMENT NO. 1 TO PROMISSORY NOTE

      Reference is made to that $56,017,698.87 Promissory Note of STAR
TELECOMMUNICATIONS, INC., a Delaware corporation with its chief executive
offices located at 223 East De La Guerra, Santa Barbara, California, 93101
(together with its successors and assigns, the "Maker"), effective February 3,
2000 (as the same may be amended, modified or supplemented from time to time,
including any extensions, refinancings, refundings or renewals thereof in whole
or in part, collectively, the "Note"), payable to MCI WORLDCOM NETWORK SERVICES,
INC., a Delaware corporation with offices located at 6929 N. Lakewood Avenue,
Mail Drop 5.2-510, Tulsa, Oklahoma 74117 (the "Holder"). Notwithstanding
anything contained in the Note to the contrary, from and after the date hereof,
unless sooner accelerated, the Note shall mature on or before the earlier to
occur of (such date being referred to herein as the "Maturity Date"): (a)
termination of the Agreement and Plan of Merger dated February 11, 2000, by and
between the Maker, STI Merger Co. and World Access, Inc. (the "Merger
Agreement"); (b) consummation of the merger transaction contemplated by the
Merger Agreement; or (c) August 31, 2000, without notice or presentment. Nothing
herein shall be considered or construed to be an agreement by Holder to extend
the Maturity Date beyond August 31, 2000.

      When attached to the Note, this Amendment No. 1 shall become a part of the
Note, and the terms and provisions of the Note as modified by this Amendment No.
1 shall remain in full force and effect.

Dated as of: July ___, 2000

ATTEST:                                STAR TELECOMMUNICATIONS, INC.

By:                                    By:
   -------------------------------        -------------------------------
Name:                                  Name:
     -----------------------------          -----------------------------
Title:                                 Title:
      ----------------------------           ----------------------------

                                       Agreed to and Accepted By:

ATTEST:                                MCI WORLDCOM NETWORK
                                       SERVICES, INC.

By:                                    By:
   -------------------------------        -------------------------------
Name:                                  Name:
     -----------------------------          -----------------------------
Title:                                 Title:
      ----------------------------           ----------------------------

                                        1<PAGE>

                    AMENDMENT NO. 2 TO STANDBY TERM LOAN NOTE

      Reference is made to that $30,000,000.00 Standby Term Loan Note of STAR
TELECOMMUNICATIONS, INC., a Delaware corporation with its chief executive
offices located at 223 East De La Guerra, Santa Barbara, California, 93101
(together with its successors and assigns, the "Maker"), dated June 30, 2000 (as
the same may be amended, modified or supplemented from time to time, including
any extensions, refinancings, refundings or renewals thereof in whole or in
part, collectively, the "Term Note"), payable to MCI WORLDCOM NETWORK SERVICES,
INC., a Delaware corporation with offices located at 6929 N. Lakewood Avenue,
Mail Drop 5.2-510, Tulsa, Oklahoma 74117 (the "Holder"). Notwithstanding
anything contained in the Term Note to the contrary, from and after the date
hereof, unless sooner accelerated, the Term Note shall mature on or before the
earlier to occur of (such date being referred to herein as the "Maturity Date"):
(a) termination of the Agreement and Plan of Merger dated February 11, 2000, by
and between the Maker, STI Merger Co. and World Access, Inc. (the "Merger
Agreement"); (b) consummation of the merger transaction contemplated by the
Merger Agreement; or (c) October 31, 2000, without notice or presentment.
Nothing herein shall be considered or construed to be an agreement by Holder to
extend the Maturity Date beyond October 31, 2000, or to make any Advances (as
defined in the Term Note) to Maker on the Maturity Date or any date after the
Maturity Date.

      Notwithstanding the extension of the Maturity Date pursuant to this
Amendment No. 2 and notwithstanding anything contained in the Term Note to the
contrary, Maker shall not be entitled to receive, nor shall Maker receive, an
Advance under the Term Note on September 1, 2000 and, September 1, 2000 shall
not be considered an Advance Date (as defined in the Term Note) under the Term
Note.

      When attached to the Term Note, this Amendment No. 2 shall become a part
of the Term Note, and the terms and provisions of the Term Note as modified by
this Amendment No. 2 shall remain in full force and effect.

Dated as of: August ___, 2000

                    [SIGNATURES APPEAR ON THE FOLLOWING PAGE]

                                        1

<PAGE>

ATTEST:                                STAR TELECOMMUNICATIONS, INC.

By:                                    By:
   -------------------------------        -------------------------------
Name:                                  Name:
     -----------------------------          -----------------------------
Title:                                 Title:
      ----------------------------           ----------------------------

                                       Agreed to and Accepted By:

ATTEST:                                MCI WORLDCOM NETWORK
                                       SERVICES, INC.

By:                                    By:
   -------------------------------        -------------------------------
Name:                                  Name:
     -----------------------------          -----------------------------
Title:                                 Title:
      ----------------------------           ----------------------------

                                        2<PAGE>

                       AMENDMENT NO. 2 TO PROMISSORY NOTE

      Reference is made to that $56,017,698.87 Promissory Note of STAR
TELECOMMUNICATIONS, INC., a Delaware corporation with its chief executive
offices located at 223 East De La Guerra, Santa Barbara, California, 93101
(together with its successors and assigns, the "Maker"), effective February 3,
2000 (as the same may be amended, modified or supplemented from time to time,
including any extensions, refinancings, refundings or renewals thereof in whole
or in part, collectively, the "Note"), payable to MCI WORLDCOM NETWORK SERVICES,
INC., a Delaware corporation with offices located at 6929 N. Lakewood Avenue,
Mail Drop 5.2-510, Tulsa, Oklahoma 74117 (the "Holder"). Notwithstanding
anything contained in the Note to the contrary, from and after the date hereof,
unless sooner accelerated, the Note shall mature on or before the earlier to
occur of (such date being referred to herein as the "Maturity Date"): (a)
termination of the Agreement and Plan of Merger dated February 11, 2000, by and
between the Maker, STI Merger Co. and World Access, Inc. (the "Merger
Agreement"); (b) consummation of the merger transaction contemplated by the
Merger Agreement; or (c) October 31, 2000, without notice or presentment.
Nothing herein shall be considered or construed to be an agreement by Holder to
extend the Maturity Date beyond October 31, 2000.

      When attached to the Note, this Amendment No. 2 shall become a part of the
Note, and the terms and provisions of the Note as modified by this Amendment No.
2 shall remain in full force and effect.

Dated as of: August ___, 2000

ATTEST:                                STAR TELECOMMUNICATIONS, INC.

By:                                    By:
   -------------------------------        -------------------------------
Name:                                  Name:
     -----------------------------          -----------------------------
Title:                                 Title:
      ----------------------------           ----------------------------

                                       Agreed to and Accepted By:

ATTEST:                                MCI WORLDCOM NETWORK
                                       SERVICES, INC.

By:                                    By:
   -------------------------------        -------------------------------
Name:                                  Name:
     -----------------------------          -----------------------------
Title:                                 Title:
      ----------------------------           ----------------------------

                                        1

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