February 20, 2002

Asghar D. Mostafa
956 Bellview Rd.
McLean, VA 22102

Dear Asghar:

ASC, Inc. acknowledges notification and acceptance of your intent to resign from
your position of Chief Executive Officer and President of the Company effective
April 20, 2002, for “good reason” as that term is defined in paragraph 11(b) the
employment agreement, dated August 31, 1998, between you and ASC (the
“Agreement”). You will continue as a member of the Board of Directors. You will
continue to be paid at your current pay rate, with benefits and service credit
through April 20, 2002, when your employment with ASC will terminate for “good
reason”. By terminating your employment for “good reason”, you will receive the
benefits and salary continuation set forth below.

•   Pursuant to paragraph 12 of the Agreement, you will receive a sum equal to
your base salary for three years (a three-year total of $600,000), which is to
be paid in a lump sum, less statutory withholdings, no later than May 20, 2002.
Your employment agreement also calls for a payment equal to two times the
average aggregate bonuses previously paid you; however, this amount is zero
given the fact that you have not received any bonus payments previously.
                                                           [ADM] Initial here  
•   Our records indicate that your vacation balance as of your termination date
will be 222.2 hours. Subject to confirmation of this balance, you will be paid
$21,365.38, less statutory withholdings, for your accrued and unused vacation
hours. Your vacation pay will be included with your final payroll check. This
payment will be contingent on your return of any company property in your
possession.   •   Your current medical, dental and vision coverage will end
April 30, 2002. However, pursuant to the Agreement, you will receive insurance
benefits for a period of up to two years. Therefore, the company will reimburse
you for the cost of continuation under COBRA, conversion to another MAMSI plan,
or for the cost of an individual policy during the two year time period
beginning May 1, 2002 through April 30, 2004. ASC will assist with the
additional tax liability associated with these reimbursements through a gross-up
allowance for federal, state and FICA tax with the payment of tax withholdings
on your behalf.   •   Your Employer-Sponsored Group Life Insurance, Voluntary
Life Insurance, Short and Long Term Disability will cease as of April 30, 2002.
You will have the option to convert the employer paid portion of the Life
insurance to an individual Whole Life policy with the Guardian. If you wish to
convert this benefit, the Guardian must receive your application by

 

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    May 31, 2002. ASC will reimburse you for the cost of this Whole Life policy
during the two year time period beginning May 1, 2002 through April 30, 2004.
There are no continuation options for Short Term or Long Term Disability;
however, if you wish to purchase an individual disability policy, ASC will
reimburse you for the cost of this benefit during the two year time period
beginning May 1, 2002 through April 30, 2004. ASC will assist with the
additional tax liability associated with these reimbursements through a gross-up
allowance for federal, state and FICA tax with the payment of tax withholdings
on your behalf. Please be advised that you may be subject to medical
underwriting when applying for individual policy benefits.   •   If you become
reemployed with another employer and become eligible to receive insurance or
other benefits under another employer’s plan, the medical and/or other insurance
benefits described herein shall be secondary to those provided under such other
plan during such applicable period of eligibility.   •   As a participant in the
company’s 401(k) plan, you will need to decide the appropriate disposition of
any 401(k) funds you may have. You will receive information directly from Cigna
concerning 401(k) plan rollover procedures. Your 401(k) payroll deduction will
cease as of your termination date, unless you notify Laurie Foglesong in Human
Resources that you would like to change your election or discontinue your
participation sooner.   •   ASC has been given advice that Section 4999 of the
Internal Revenue Code is not applicable to your separation payments. You are
however, free to verify this opinion and in fact, we recommend that you seek an
opinion from an attorney of your own choosing.   •   Enclosed you will find a
Personnel Option Status statement which provides a detailed summary of the
status of each of your stock options. You must exercise any vested, unexercised
options under the 1998 Nonqualified Stock Option Plan, the Second 1998
Nonqualified Stock Option Plan and/or the 1999 Nonqualified Stock Option Plan by
April 20, 2002 or you will forfeit these options. You must exercise any vested,
unexercised options under the 2000 Stock Incentive Plan by July 19, 2002. Please
contact Laurie Foglesong in Human Resources if you wish to exercise your
options. All unvested options will be forfeited upon your termination date.   •
  Please return all Company property in your possession on or before April 20,
2002.   •   The Company will cancel your American Express corporate card, if
applicable, effective April 20, 2002. You are responsible for any outstanding
balance on your American Express corporate card. If have any outstanding
business-related expenses, please submit a final expense report to Cindy Poling.
Upon receipt of this information, Advanced Switching Communications will be able
to process your final expense reimbursement.

 

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•   You are reminded that the confidentiality provisions set forth in paragraph
8 of the Agreement survive termination of employment. If a court of competent
jurisdiction finds that you have violated any of the provisions contained in
paragraph 8 of the Agreement, ASC shall terminate any further payments or
benefits pursuant to paragraph 12 of the Agreement, and you will be required to
return any and all payments received by you since the time of the violation.

Please feel free to contact Laurie Foglesong in Human Resources at 703.288.8145,
if you have any questions or concerns with any of the above-mentioned items.

Sincerely,

/s/ Arthur J. Marks

Arthur J. Marks

      Enclosure:   ASC Employee Benefit Information     Personnel Option Status
Statement