Document:

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                                                                   EXHIBIT 10.21

                               VERTEL CORPORATION

                              EMPLOYMENT AGREEMENT
                              --------------------

     This Employment Agreement (the "Agreement") is dated as of January 1, 2002
                                     ---------
by and between Stephen J. McDaniel ("Employee") and Vertel Corporation (the
                                     --------
"Company") and supersedes the Employment Agreement with Company dated November
 -------
1, 1999 and the Employment Status letter from Marc Maassen dated December 28,
2001.

     1.  Term of Agreement.
         -----------------

         (a)   Term. This Agreement will commence on the date hereof and
               ----
continue until termination of the Agreement as provided for in Sections 1(b) or
5 below; provided however that the parties may terminate this Agreement by
mutual written agreement at any time.

         (b)   Change of Control. The parties have previously entered into a
               -----------------
Retention Agreement dated November 1, 1999 (the "Retention Agreement") intended
                                                 -------------------
to provide certain benefits to Employee if his employment is terminated under
certain circumstances following a Change of Control (as defined in the Retention
Agreement) of the Company. This Agreement governs any termination of Employee's
employment that occurs prior to a Change of Control. This Agreement terminates
in its entirety upon a Change of Control and the Retention Agreement governs any
termination of Employee's employment that occurs on or following a Change of
Control.

     2.  Duties.
         ------

         (a)   Position. Employee will be employed as Vice President, Sales -
               --------
Americas of the Company, and as such will report to the Senior Vice President,
Sales and Strategic Alliances.

         (b)   Obligations to the Company. Employee agrees to the best of his
               --------------------------
ability and experience that he will, to the reasonable satisfaction of the
Company, at all times loyally and conscientiously perform all of the duties and
obligations required of him pursuant to the terms of this Agreement. Employee
will comply with and be bound by the Company's operating policies, procedures
and practices from time to time in effect during the term of Employee's
employment.

<PAGE>

     3.  At-Will Employment. The Company and Employee acknowledge that
         ------------------
Employee's employment is and will continue to be at-will, as defined under
applicable law, and that Employee's employment with the Company may be
terminated by either party at any time for any or no reason. If Employee's
employment terminates for any reason, Employee will not be entitled to any
payments, benefits, damages, award or compensation other than as provided in
this Agreement. The rights and duties created by this Section 3 may not be
modified in any way except by a written agreement executed by the Chief
Executive Officer on behalf of the Company.

     4.  Compensation and Benefits. Employee's compensation will be as
         -------------------------
determined from time to time by the Chief Executive Officer. Employee will be
eligible to participate in the Company's employee benefit plans of general
application, including without limitation, those plans covering medical,
disability and life insurance in accordance with the rules established for
individual participation in any such plan and under applicable law. Employee
will be eligible for vacation and sick leave in accordance with the Company's
policies in effect from time to time and will receive such other benefits as the
Company generally provides to its other employees of comparable position and
experience.

     5.  Termination of Employment and Severance Benefits.
         ------------------------------------------------

         (a)   Termination of Employment. Employee's employment and this
               -------------------------
Agreement may be terminated upon the occurrence of any of the following events:

               (i)   The Company's determination that it is terminating Employee
for Cause (as defined in Section 6(a) below) ("Termination for Cause");
                                               ---------------------

               (ii)  The Company's determination that it is terminating Employee
without Cause, which determination may be made by the Company at any time at the
Company's sole discretion, for any or no reason ("Termination Without Cause");
                                                  -------------------------

               (iii) The effective date of a written notice sent to the Company
from Employee stating that Employee is electing to terminate his employment with
the Company ("Voluntary Termination");
              ---------------------

               (iv)  A change in Employee's status such that a Constructive
Termination (as defined in Section 6(b) below) has occurred; or

               (v)   As a result of Employee's death or disability (as defined
in Section 6(c) below).

                                      -2-

<PAGE>

         (b)   Severance Benefits. Employee will be entitled to receive
               ------------------
severance benefits upon termination of employment only as set forth in this
Section 5(b);

               (i)   Voluntary Termination. If Employee's employment terminates
                     ---------------------
by Voluntary Termination, then Employee will not be entitled to receive payment
of any severance benefits. Employee will receive payment(s) for all salary and
unpaid vacation accrued as of the date of Employee's termination of employment.
Employee's benefits will be continued only to the extent provided upon
termination of employment pursuant to the Company's then existing benefit plans
and policies in accordance with such plans and policies in effect on the date of
termination and as provided by applicable law.

               (ii)  Involuntary Termination. Subject to Sections 7 and 8 below,
                     -----------------------
if Employee's employment is terminated under Section 5(a)(ii) or 5(a)(iv) above
(such termination, an "Involuntary Termination"), Employee will be entitled to
                       -----------------------
receive payment of severance benefits only as set forth in this Section
5(b)(ii).

                     (A) Salary Continuance. If Employee experiences an
                         ------------------
Involuntary Termination, Employee will be entitled to receive an amount equal to
his regular salary (subject to any applicable tax withholding) as of the time of
termination for nine (9) months following such termination ("Severance Period").
                                                             ----------------
Such payment will be made during the Severance Period on normal Company payroll
paydays.

                     (B) Pro-Rated Quarterly Bonus. Employee will be entitled to
                         -------------------------
receive payment within two weeks of the date of termination of the pro-rated
portion of any target quarterly bonus accrued to Employee through such date of
termination, as determined by the Chief Executive Officer in his sole discretion
based on the specific corporate or individual performance targets for such
quarter.

                     (C) Other Benefits. In the event Employee elects to obtain
                         --------------
medical or dental insurance benefit continuation pursuant to COBRA and completes
the necessary documentation, the Company will pay Employee's COBRA premiums,
less the premium Employee paid while an employee of Company, for continuation of
Employee's current group medical and dental insurance coverage through the
Severance Period. In the event Employee desires to continue such COBRA coverage
after the Severance Period, all premiums for such coverage will be paid by
Employee.

               (iii) Termination for Cause. If Employee's employment is
                     ---------------------
terminated for Cause, then Employee will not be entitled to receive a payment of
any

                                      -3-

<PAGE>

severance benefits. Employee will receive payment(s) for all salary and
unpaid vacation accrued as of the date of Employee's termination of employment
and Employee's benefits will cease as of the termination date, except for
employee's right to continue health benefits under COBRA in accordance with
applicable law.

               (iv)  Termination by Reason of Death or Disability. In the event
                     --------------------------------------------
that Employee's employment with the Company terminates as a result of Employee's
death or disability (as defined in Section 6(c) below), Employee or Employee's
estate or representative will receive all salary and unpaid vacation accrued as
of the date of Employee's death or disability and any other benefits payable
under the Company's then existing benefit plans and policies in accordance with
such plans and policies in effect on the date of death or disability and in
accordance with applicable law. In addition, Employee's estate or representative
will receive the pro-rated portion of any target quarterly bonus accrued to
Employee through such date of termination, as determined by the Chief Executive
Officer in his sole discretion based on the specific corporate or individual
performance targets for such quarter.

     6.  Definitions. For purposes of this Agreement, the following definitions
         -----------
will apply:

         (a)   "Cause" for Employee's termination will exist if the Company
                -----
terminates Employee's employment for any of the following reasons:

               (i)   Employee's gross misconduct or fraud;

               (ii)  Employee's failure to comply with an express and
reasonable direction of the Company's Senior Vice President, Sales and Strategic
Alliance or Chief Executive Officer as part of Employee's responsibilities;

               (iii) Employee's failure to substantially perform his duties
hereunder (other than any such failure due to Employee's physical or mental
illness) and such failure is not remedied within 10 business days after written
notice from the Company's Senior Vice President, Sales and Strategic Alliances
or Chief Executive Officer;

               (iv)  Employee's conviction or entering a plea of guilty or no lo
contendre to a felony; or

               (v)   Employee's material breach of any of his obligations
hereunder or any other written agreement or covenant with the Company or any of
its affiliates.

                                       -4-

<PAGE>

         (b)   "Constructive Termination" will be deemed to occur if Employee
                ------------------------
voluntarily resigns within 30 days following (i) a material reduction in
Employee's job responsibilities, it being understood that a mere change in title
alone shall not constitute a material reduction in job responsibilities, (ii)
without Employee's prior written approval, the Company requires Employee to
relocate to a facility or location more than 50 miles from the Company's current
location, it being understood that required travel on the Company's business to
an extent consistent with Employee's job responsibilities does not constitute
Constructive Termination, or (iii) a reduction in Employee's then current base
salary, except than an across-the-board reduction in the salary level of all of
the Company's senior management team in the same percentage as part of a general
salary level reduction shall not constitute Constructive Termination. Also, a
change in Employee's commission and/or bonus plan as detailed in Employee's
annual Compensation Plan document shall not constitute Constructive Termination.

         (c)   "Disability" will mean that Employee has been unable to perform
                ----------
his duties hereunder as a result of his incapacity due to physical or mental
illness, and after its commencement such inability, which continues for at least
120 consecutive calendar days or 150 calendar days during any consecutive
twelve-month period, is determined to be total and permanent by a physician
selected by the Company and its insurers and acceptable to Employee or
Employee's legal representative (with such agreement on acceptability not to be
unreasonably withheld.)

     7.  Proprietary Information and Inventions Agreement; Breach of
         -----------------------------------------------------------
Confidentiality Provisions. Employee has previously signed a Vertel Employee
--------------------------
Proprietary Information and Inventions Agreement (the "Confidentiality
                                                       ---------------
Agreement") substantially in the form attached hereto as Exhibit A. Employee
---------                                                ---------
hereby represents and warrants to the Company that he has complied with all
obligations under the Confidentiality Agreement and agrees to continue to abide
by the terms of the Confidentiality Agreement and further agrees that the
provisions of the Confidentiality Agreement will survive any termination of this
Agreement or of Employee's employment relationship with the Company. Employee
acknowledges that upon breach of the confidentiality provisions contained in
this Section 7, the Company would sustain irreparable harm from such breach,
and, therefore, Employee agrees that in addition to any other remedies which the
Company may have under this Agreement, the Confidentiality Agreement or
otherwise, the Company will be entitled to obtain equitable relief, including
specific performance and injunctions, restraining him from committing or
continuing any such violation of this Agreement or the Confidentiality
Agreement. Employee further agrees that upon his material or intentional breach
of any of the provisions of this Section 7 and following written notice of such
breach by the Company to Employee and an opportunity to cure such

                                      -5-

<PAGE>

breach within 5 business days where such breach may be cured, in addition to any
other remedies the Company may have, the Company's obligations to provide
payments and benefits to Employee as described in Section 5(b) of this Agreement
will immediately terminate and, to the extent payments and benefits have already
been paid to Employee at the time of a breach occurring within the Severance
Period, the Company will have the right to recover from Employee the value, in
cash, of such payments or benefits that relate to the portion of the Severance
Period beginning on the date of the breach and ending on the termination of the
Severance Period.

     8.   Nonsolicitation Covenant; Breach of Agreement.
          ---------------------------------------------

          (a)  Nonsolicitation Covenants. In consideration for the Company's
               -------------------------
entering into this Agreement and for the payment of any benefits hereunder,
Employee hereby agrees that he will not, during the term of his employment
pursuant to this Agreement, and the Severance Period, if any, do any of the
following without the prior written consent of the Chief Executive Officer:

               Solicit or influence or attempt to influence any person or entity
employed or engaged as a consultant by the Company to terminate or otherwise
cease his, her or its employment or consulting relationship with the Company or
become an employee or consultant of any competitor of the Company. This Section
8(a) is to be read in conjunction with Section 9 of the Confidentiality
Agreement executed by Employee.

               Solicit or influence or attempt to influence any client, customer
or other person either directly or indirectly, to direct his, her or its
purchase of the Company's products and/or services to any person, firm,
corporation, institution or other entity in competition with the business of the
Company.

               Carry on any business or activity (whether directly or
indirectly, as a partner, stockholder, principal, agent, director, affiliate,
employee or consultant) which is competitive with the business conducted by the
Company (as conducted now or during the term of Employee's employment), nor
engage in any other activities that conflict with Employee's obligations to the
Company.

          (b)  Breach of Nonsolicitation Provisions. Employee acknowledges that
               ------------------------------------
the Company's entering into this Agreement and committing to make any payments
required hereunder represents consideration for Employee's agreement to abide by
the restrictions set forth in Section 8(a). In the event Employee chooses to
engage in any action or activity prohibited under Section 8(a) above during the
term of employment or the Severance Period (a "Prohibited Activity"), Employee
                                               -------------------
agrees that

                                      -6-

<PAGE>

he will forego any payments or benefits to which he would otherwise have been
entitled hereunder from and following the date of, or the date of commencement
of, the Prohibited Activity (such date, the "Prohibited Activity Date") and, to
                                             ------------------------
the extent payments and benefits have already been paid to Employee as of the
Prohibited Activity Date, Employee agrees to return to the Company the value, in
cash, of any such payments or benefits that relate to the period beginning on
the Prohibited Activity Date and ending on the termination of the Severance
Period.

     9.   Conflicts. Employee represents that his performance of all the terms
          ---------
of this Agreement will not breach any other agreement to which Employee is a
party. Employee has not, and will not during the term of this Agreement, enter
into any oral or written agreement in conflict with any of the provisions of
this Agreement. Employee further represents that he is entering into or has
entered into an employment relationship with the Company of his own free will
and that he has not been solicited as an employee in any way by the Company.

     10.  Successors. Any successor to the Company (whether direct or indirect
          ----------
and whether by purchase, lease, merger, consolidation, liquidation or otherwise)
or to all or substantially all of the Company's business and/or assets will
assume the obligations under this Agreement and agrees expressly to perform the
obligations under this Agreement in the same manner and to the same extent as
the Company would be required to perform such obligations in the absence of a
succession. The terms of this Agreement and all of Employee's rights hereunder
will inure to the benefit of, and be enforceable by, Employee's personal or
legal representatives, executors, administrators, successors, heirs,
distributees, devisees and legatees.

     11.  Entire Agreement. This Agreement, including any Exhibits hereto,
          ----------------
constitutes the sole agreement of the parties and supersedes all oral
negotiations and prior writings with respect to Employee's employment with the
Company and the subject matter hereof. Provided, however, that the entering into
by the parties of this Agreement does not supersede, replace, invalidate the
effectiveness of, amend or otherwise alter the Retention Agreement or the
Confidentiality Agreement previously executed by Employee, and it is the intent
of the parties that the Retention Agreement and the Confidentiality Agreement
shall remain in full force and effect following execution of this Agreement.

     12.  Miscellaneous Provisions.
          ------------------------

          (a)  No Duty to Mitigate. Employee will not be required to mitigate
               -------------------
the amount of any payment contemplated by this Agreement (whether by seeking new
employment or in any other manner), nor, except as otherwise provided in this

                                      -7-

<PAGE>

Agreement, will any such payment be reduced by any earnings that Employee may
receive from any other source.

          (b)  Amendments and Waivers. Any term of this Agreement may be amended
               ----------------------
or waived only with the written consent of the parties.

          (c)  Notices. Any notice required or permitted by this Agreement will
               -------
be in writing and will be deemed sufficient upon receipt, when delivered
personally or by a nationally-recognized delivery service (such as Federal
Express or UPS), or 48 hours after being deposited in the U.S. mail as certified
or registered mail with postage prepaid, if such notice is addressed to the
party to be notified at such party's address as set forth below or as
subsequently modified by written notice.

          (d)  Choice of Law. The validity, interpretation, construction and
               -------------
performance of this Agreement will be governed by the laws of the State of
California, without giving effect to the principle of conflict of laws.

          (e)  Severability. If one or more provisions of this Agreement are
               ------------
held to be unenforceable under applicable law, the parties agree to renegotiate
such provision in good faith. In the event that the parties cannot reach a
mutually agreeable and enforceable replacement for such provision, then (i) such
provision will be excluded from this Agreement, (ii) the balance of the
Agreement will be interpreted as if such provision were so excluded, and (iii)
the balance of the Agreement will be enforceable in accordance with its terms.

          (f)  Counterparts. This Agreement may be executed in counterparts,
               ------------
each of which will be deemed an original, but all of which together will
constitute one and the same instrument.

          (g)  Advice of Counsel. EACH PARTY TO THIS AGREEMENT ACKNOWLEDGES THAT
               -----------------
IN EXECUTING THIS AGREEMENT, SUCH PARTY HAS HAD THE OPPORTUNITY TO SEEK THE
ADVICE OF INDEPENDENT LEGAL COUNSEL, AND HAS READ AND UNDERSTOOD ALL OF THE
TERMS AND PROVISIONS OF THIS AGREEMENT. THIS AGREEMENT WILL NOT BE CONSTRUED
AGAINST ANY PARTY BY REASON OF THE DRAFTING OR PREPARATION HEREOF.

                            [Signature Page Follows]

                                      -8-

<PAGE>

The parties have executed this Agreement the date first written above.

                                       VERTEL CORPORATION

                                       By: /s/ Marc E. Maassen

                                       Title: President and CEO

                                       Address:  21300 Victory Boulevard, #700
                                                 Woodland Hills, CA  91367

                                       NAME:  Steve McDaniel

                                       Signature: /s/ Stephen J. McDaniel

                                       Address: ____________________________

                                                ____________________________

                                       -9-

<PAGE>

                                    EXHIBIT A

                   VERTEL EMPLOYEE PROPRIETARY INFORMATION AND
                              INVENTIONS AGREEMENT

                                      -10-<PAGE>

                                                                   EXHIBIT 10.22

                               VERTEL CORPORATION

                              EMPLOYMENT AGREEMENT
                              --------------------

     This Employment Agreement (the "Agreement") is dated as of January 1, 2002
                                     ---------
by and between E. Carey Walters ("Officer") and Vertel Corporation (the
                                  -------
"Company").
 -------

     1.   Term of Agreement.
          -----------------

          (a)  Term. This Agreement will commence on the date hereof and
               ----
continue until termination of the Agreement as provided for in Sections 1(b) or
5 below; provided however that the parties may terminate this Agreement by
mutual written agreement at any time. The first year of this Agreement shall be
referred to herein as the "Original Term."
                           -------------

          (b)  Change of Control. The parties have previously entered into a
               -----------------
Retention Agreement dated January 1, 2002 (the "Retention Agreement") intended
                                                -------------------
to provide certain benefits to Officer if his or her employment is terminated
under certain circumstances following a Change of Control (as defined in the
Retention Agreement) of the Company. This Agreement governs any termination of
Officer's employment that occurs prior to a Change of Control and any successor
to the Company will be obligated to perform the Company's obligations hereunder
as provided in Section 11 below. This Agreement terminates in its entirety upon
a Change of Control and the Retention Agreement governs any termination of
Officer's employment that occurs on or following a Change of Control.

     2.   Duties.
          ------

          (a)  Position. Officer will be employed as Senior Vice President,
               --------
Strategic Alliances of the Company, and as such will report to the Chief
Executive Officer.

          (b)  Obligations to the Company. Officer agrees to the best of his or
               --------------------------
her ability and experience that he or she will, to the reasonable satisfaction
of the Company, at all times loyally and conscientiously perform all of the
duties and obligations required of him or her pursuant to the terms of this
Agreement. Officer will comply with and be bound by the Company's operating
policies, procedures and practices from time to time in effect during the term
of Officer's employment.

     3.   At-Will Employment. The Company and Officer acknowledge that Officer's
          ------------------
employment is and will continue to be at-will, as defined under applicable law,
and that Officer's employment with the Company may be terminated by either party
at any time for any or no reason. If Officer's employment terminates for any
reason, Officer will not be entitled to any payments, benefits, damages, award
or compensation other than as provided in this Agreement. The rights and duties
created by this Section 3 may not be modified in any way except by a written
agreement executed by the Chief Executive Officer on behalf of the Company.

<PAGE>

     4.   Compensation and Benefits. Officer's compensation will be as
          -------------------------
determined from time to time by the Chief Executive Officer. Officer will be
eligible to participate in the Company's employee benefit plans of general
application, including without limitation, those plans covering medical,
disability and life insurance in accordance with the rules established for
individual participation in any such plan and under applicable law. Officer will
be eligible for vacation and sick leave in accordance with the Company's
policies in effect from time to time and will receive such other benefits as the
Company generally provides to its other employees of comparable position and
experience.

     5.   Termination of Employment and Severance Benefits.
          ------------------------------------------------

          (a)  Termination of Employment. Officer's employment and this
               -------------------------
Agreement may be terminated upon the occurrence of any of the following events:

               (i)   The Company's determination in good faith that it is
terminating Officer for Cause (as defined in Section 6(a) below) ("Termination
                                                                   -----------
for Cause");
---------

               (ii)  The Company's determination that it is terminating Officer

without Cause, which determination may be made by the Company at any time at the
Company's sole discretion, for any or no reason ("Termination Without Cause");
                                                  -------------------------

               (iii) The effective date of a written notice sent to the Company
from Officer stating that Officer is electing to terminate his or her employment
with the Company ("Voluntary Termination");
                   ---------------------

               (iv)  A change in Officer's status such that a Constructive
Termination (as defined in Section 6(b) below) has occurred; or

               (v)   As a result of Officer's death or Disability (as defined in
Section 6(c) below).

          (b)  Severance Benefits. Officer will be entitled to receive severance
               ------------------
benefits upon termination of employment only as set forth in this Section 5(b):

               (i)   Voluntary Termination. If Officer's employment terminates
                     ---------------------
by Voluntary Termination, then Officer will not be entitled to receive payment
of any severance benefits. Officer will receive payment(s) for all salary and
unpaid vacation accrued as of the date of Officer's termination of employment
and Officer's benefits will be continued under the Company's then existing
benefit plans and policies in accordance with such plans and policies in effect
on the date of termination and in accordance with applicable law.

               (ii)  Involuntary Termination during Original Term. Subject to
                     --------------------------------------------
Sections 7 and 8 below, if Officer's employment is terminated under Section
5(a)(ii) or 5(a)(iv) above (such termination, an "Involuntary Termination"),
                                                  -----------------------
Officer will be entitled to receive payment of severance benefits only as set
forth in this Section 5(b)(ii).

                                      -2-

<PAGE>

                     (A)  Salary Continuance. If Officer experiences an
                          ------------------
Involuntary Termination during the Original Term, Officer will be entitled to
receive an amount equal to his or her regular monthly salary (subject to any
applicable tax withholding) as of the time of termination for twelve (12) months
following such termination (the "Original Term Severance Period"). If Officer
                                 ------------------------------
experiences an Involuntary Termination during any period of the Agreement
following the Original Term, Officer will be entitled to receive an amount equal
to his or her regular monthly salary as of the time of termination for six (6)
months following such termination (the "Subsequent Term Severance Period" and
                                        --------------------------------
together with the Original Term Severance Period, the "Applicable Severance
                                                       --------------------
Period"). Such payments will be made during the Applicable Severance Period on
------
normal Company payroll paydays.

                     (B)  Pro-Rated Quarterly Bonus. Officer will also be
                          -------------------------
entitled to receive payment within two weeks of the date of termination of the
pro-rated portion of any target quarterly bonus accrued to Officer through such
date of termination, as determined by the Chief Executive Officer based on the
specific corporate or individual performance targets for such quarter.

                     (C)  Other Benefits. In the event Officer elects to obtain
                          --------------
medical and dental insurance benefit continuation pursuant to COBRA and
completes the necessary documentation, the Company will pay Employee's COBRA
premiums, less the premium Officer paid while an employee of Company, for
continuation of Officer's current group medical and dental insurance coverage
through the Applicable Severance Period. In the event Officer desires to
continue such COBRA coverage after the Applicable Severance Period, all premiums
for such coverage will be paid by Officer.

               (iii) Termination for Cause. If Officer's employment is
                     ---------------------
terminated for Cause, then Officer will not be entitled to receive payment of
any severance benefits. Officer will receive payment(s) for all salary and
unpaid vacation accrued as of the date of Officer's termination of employment
and Officer's benefits will be continued under the Company's then existing
benefit plans and policies in accordance with such plans and policies in effect
on the date of termination and in accordance with applicable law.

               (iv)  Termination by Reason of Death or Disability. In the event
                     --------------------------------------------
that Officer's employment with the Company terminates as a result of Officer's
death or Disability (as defined in Section 6(c) below), Officer or Officer's
estate or representative will receive all salary and unpaid vacation accrued as
of the date of Officer's death or Disability and any other benefits payable
under the Company's then existing benefit plans and policies in accordance with
such plans and policies in effect on the date of death or Disability and in
accordance with applicable law. In addition, Officer's estate or representative
will receive the pro-rated portion of any target quarterly bonus accrued to
Officer through such date of termination, as determined by the Chief Executive
Officer based on the specific corporate or individual performance targets for
such quarter.

     6.   Definitions. For purposes of this Agreement, the following definitions
          -----------
will apply:

                                      -3-

<PAGE>

          (a)  "Cause" for Officer's termination will exist if the Company
                -----
terminates Officer's employment for any of the following reasons: (i) Officer's
willful failure substantially to perform his or her duties hereunder (other than
any such failure due to Officer's physical or mental illness), and such willful
failure is not remedied within 10 business days after written notice from the
Chief Executive Officer, which written notice shall state that failure to remedy
such conduct may result in Termination for Cause, (ii) Officer's engaging in
willful and serious misconduct that has caused or is reasonably expected to
result in material injury to the Company or any of its affiliates, (iii)
Officer's conviction of or entering a plea of guilty or nolo contender to a
crime that constitutes a felony, or (iv) Officer's willful breach of any of his
or her obligations hereunder or under any other written agreement or covenant
with the Company or any of its affiliates and such willful breach is not
remedied within 10 business days after written notice from the Chief Executive
Officer, which written notice shall state that failure to remedy such conduct
may result in Termination for Cause.

          (b)  "Constructive Termination" will be deemed to occur if Officer
                ------------------------
voluntarily resigns within 30 days following (i) a material reduction in
Officer's job responsibilities, it being understood that a mere change in title
alone shall not constitute a material reduction in job responsibilities, (ii)
without Officer's prior written approval, the Company requires Officer to
relocate to a facility or location more than 50 miles from the Company's current
location, it being understood that required travel on the Company's business to
an extent consistent with Officer's job responsibilities does not constitute
Constructive Termination, or (iii) a reduction in Officer's then-current base
salary, except that an across-the-board reduction in the salary level of all of
the Company's executive officers in the same percentage amount as part of a
general salary level reduction shall not constitute Constructive Termination.

          (c)  "Disability" will mean that Officer has been unable to perform
                ----------
his or her duties hereunder as the result of his or her incapacity due to
physical or mental illness, and after its commencement such inability, which
continues for at least 120 consecutive calendar days or 150 calendar days during
any consecutive twelve-month period, is determined to be total and permanent by
a physician selected by the Company and its insurers and acceptable to Officer
or to Officer's legal representative (with such agreement on acceptability not
to be unreasonably withheld).

     7.   Confidentiality Agreement; Breach of Confidentiality Provisions.
          ---------------------------------------------------------------
Officer will sign, or has signed, a Confidential Information and Invention
Assignment Agreement (the "Confidentiality Agreement") substantially in the form
                           -------------------------
attached hereto as Exhibit A. Officer hereby represents and warrants to the
                   ---------
Company that he or she has complied with all obligations under the
Confidentiality Agreement and agrees to continue to abide by the terms of the
Confidentiality Agreement and further agrees that the provisions of the
Confidentiality Agreement will survive any termination of this Agreement or of
Officer's employment relationship with the Company. Officer acknowledges that
upon breach of the confidentiality provisions contained in this Section 7, the
Company would sustain irreparable harm from such breach, and, therefore, Officer
agrees that in addition to any other remedies which the Company may have under
this Agreement, the Confidentiality Agreement or otherwise, the Company will be
entitled to obtain equitable relief, including specific performance and
injunctions, restraining him or her from committing or continuing any such
violation of this Agreement or the

                                      -4-

<PAGE>

Confidentiality Agreement. Officer further agrees that upon his or her material
or intentional breach of any of the provisions of this Section 7 and following
written notice of such breach by the Company to Officer and an opportunity to
cure such breach within 5 business days where such breach may be cured, in
addition to any other remedies the Company may have, the Company's obligations
to provide payments and benefits to Officer as described in Section 5(b) of this
Agreement will immediately terminate and, to the extent payments and benefits
have already been paid to Officer at the time of a breach occurring within the
Applicable Severance Period in a lump sum relating to the entire Applicable
Severance Period, the Company will have the right to recover from Officer the
value, in cash, of such payments or benefits that relate to the portion of the
Applicable Severance Period beginning on the date of breach and ending on the
termination of the Applicable Severance Period.

     8.   Noncompetition and Nonsolicitation Covenants; Breach of Agreement.
          -----------------------------------------------------------------

          (a)  Noncompetition and Nonsolicitation Covenants. In consideration
               --------------------------------------------
for the Company's entering into this Agreement and for the payment of any
benefits hereunder, Officer hereby agrees that he or she will not, during the
term of his or her employment pursuant to this Agreement and the Applicable
Severance Period, if any, do any of the following without the prior written
consent of the Chief Executive Officer:

               (i)   Compete. Carry on any business or activity (whether
                     -------
directly or indirectly, as a partner, stockholder, principal, agent, director,
affiliate, employee or consultant) which is competitive with the business
conducted by the Company (as conducted now or during the term of Officer's
employment), nor engage in any other activities that conflict with Officer's
obligations to the Company.

               (ii)  Solicit Business. Solicit or influence or attempt to
                     ----------------
influence any client, customer or other person either directly or indirectly, to
direct his, her or its purchase of the Company's products and/or services to any
person, firm, corporation, institution or other entity in competition with the
business of the Company.

               (iii) Solicit Personnel. Solicit or influence or attempt to
                     -----------------
influence any person or entity employed or engaged as a consultant by the
Company to terminate or otherwise cease his, her or its employment or consulting
relationship with the Company or become an employee or consultant of any
competitor of the Company. This Section 8(a)(iii) is to be read in conjunction
with Section 9 of the Vertel Employee Proprietary Information and Inventions
Agreement ("Confidentiality Agreement") executed by Officer.
            -------------------------

          (b)  Breach of Noncompetition and Nonsolicitation Provisions. Officer
               -------------------------------------------------------
acknowledges that the Company's entering into this Agreement and committing to
make any payments required hereunder represents consideration for Officer's
agreement to abide by the restrictions set forth in Section 8(a). Nothing in
this Agreement shall prohibit Officer from engaging in any action or activity
prohibited under Section 8(a)(i), (ii) or (iii) above during the term of
employment or the Applicable Severance Period (a "Prohibited Activity");
                                                  -------------------
provided however that if Officer chooses to engage in a Prohibited Activity,
Officer agrees that he or she will forego any payments or benefits to which he
or she would otherwise have been entitled

                                      -5-

<PAGE>

hereunder from and following the date of, or the date of commencement of, the
Prohibited Activity (such date, the "Prohibited Activity Date") and, to the
                                     ------------------------
extent payments and benefits have already been paid to Officer in a lump sum
relating to the entire Applicable Severance Period as of the Prohibited Activity
Date, Officer agrees to return to the Company the value, in cash, of any such
payments or benefits that relate to the period beginning on the Prohibited
Activity Date and ending on the termination of the Applicable Severance Period.

     9.    Conflicts. Officer represents that his or her performance of all the
           ---------
terms of this Agreement will not breach any other agreement to which Officer is
a party. Officer has not, and will not during the term of this Agreement, enter
into any oral or written agreement in conflict with any of the provisions of
this Agreement. Officer further represents that he or she is entering into or
has entered into an employment relationship with the Company of his or her own
free will and that he or she has not been solicited as an employee in any way by
the Company.

     10.   Release. In consideration for the Company's entering into this
           -------
Agreement and as a condition to receipt of any benefits to which Officer may be
entitled under Section 5(b) above, Officer agrees that upon his or her
termination of employment with the Company, he or she will execute an agreement
in a form acceptable to the Company pursuant to which Officer will agree to
release the Company and its officers, agents and successors from claims related
to or arising from Officer's employment relationship with the Company that
occurred through and including the date of termination of employment.

     11.   Successors. Any successor to the Company (whether direct or indirect
           ----------
and whether by purchase, lease, merger, consolidation, liquidation or otherwise)
or to all or substantially all of the Company's business and/or assets will
assume the obligations under this Agreement and agrees expressly to perform the
obligations under this Agreement in the same manner and to the same extent as
the Company would be required to perform such obligations in the absence of a
succession. The terms of this Agreement and all of Officer's rights hereunder
will inure to the benefit of, and be enforceable by, Officer's personal or legal
representatives, executors, administrators, successors, heirs, distributees,
devisees and legatees.

     12.   Entire Agreement. This Agreement, including any Exhibits hereto,
           ----------------
constitutes the sole agreement of the parties and supersedes all oral
negotiations and prior writings with respect to the subject matter hereof. The
entering into by the parties of this Agreement does not supersede, replace,
invalidate the effectiveness of, amend or otherwise alter the Retention
Agreement and it is the intent of the parties that the Retention Agreement shall
remain in full force and effect following execution of this Agreement.

     13.   Miscellaneous Provisions.
           ------------------------

          (a)   No Duty to Mitigate. Officer will not be required to mitigate
                -------------------
the amount of any payment contemplated by this Agreement (whether by seeking new
employment or in any other manner), nor, except as otherwise provided in this
Agreement, will any such payment be reduced by any earnings that Officer may
receive from any other source.

                                      -6-

<PAGE>

           (b)  Amendments and Waivers. Any term of this Agreement may be
                ----------------------
amended or waived only with the written consent of the parties.

           (c)  Notices. Any notice required or permitted by this Agreement will
                -------
be in writing and will be deemed sufficient upon receipt, when delivered
personally or by a nationally-recognized delivery service (such as Federal
Express or UPS), or 48 hours after being deposited in the U.S. mail as certified
or registered mail with postage prepaid, if such notice is addressed to the
party to be notified at such party's address as set forth below or as
subsequently modified by written notice.

           (d)  Choice of Law. The validity, interpretation, construction and
                -------------
performance of this Agreement will be governed by the laws of the State of
California, without giving effect to the principles of conflict of laws.

           (e)  Severability. If one or more provisions of this Agreement are
                ------------
held to be unenforceable under applicable law, the parties agree to renegotiate
such provision in good faith. In the event that the parties cannot reach a
mutually agreeable and enforceable replacement for such provision, then (i) such
provision will be excluded from this Agreement, (ii) the balance of the
Agreement will be interpreted as if such provision were so excluded and (iii)
the balance of the Agreement will be enforceable in accordance with its terms.

           (f)  Counterparts. This Agreement may be executed in counterparts,
                ------------
each of which will be deemed an original, but all of which together will
constitute one and the same instrument.

           (g)  Arbitration. Any dispute or claim arising out of or in
                -----------
connection with this Agreement will be finally settled by binding arbitration in
Los Angeles County, California in accordance with the rules of the American
Arbitration Association by one arbitrator appointed in accordance with said
rules. The arbitrator will apply California law, without reference to rules of
conflicts of law or rules of statutory arbitration, to the resolution of any
dispute. Judgment on the award rendered by the arbitrator may be entered in any
court having jurisdiction thereof. Notwithstanding the foregoing, the parties
may apply to any court of competent jurisdiction for preliminary or interim
equitable relief, or to compel arbitration in accordance with this paragraph,
without breach of this arbitration provision. This Section 13(h) will not apply
to the Confidentiality Agreement.

           (h)  Advice of Counsel. EACH PARTY TO THIS AGREEMENT ACKNOWLEDGES
                -----------------
THAT, IN EXECUTING THIS AGREEMENT, SUCH PARTY HAS HAD THE OPPORTUNITY TO SEEK
THE ADVICE OF INDEPENDENT LEGAL COUNSEL, AND HAS READ AND UNDERSTOOD ALL OF THE
TERMS AND PROVISIONS OF THIS AGREEMENT. THIS AGREEMENT WILL NOT BE CONSTRUED
AGAINST ANY PARTY BY REASON OF THE DRAFTING OR PREPARATION HEREOF.

                            [Signature Page Follows]

                                      -7-

<PAGE>

         The parties have executed this Agreement the date first written above.

                                   VERTEL CORPORATION

                                   By: /s/ Marc E. Maassen

                                   Title:  President and Chief Executive Officer
                                           -------------------------------------

                                   Address:  21300 Victory Blvd., #700
                                             Woodland Hills, CA 91367

                                   NAME

                                   Signature: /s/ E. Carey Walters

                                   Address: ____________________________________

                                            ____________________________________

                                      -8-

<PAGE>

                                    EXHIBIT A
                                    ---------

                  VERTEL EMPLOYEE PROPRIETARY INFORMATION AND
                              INVENTIONS AGREEMENT

                                      -9-

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