TRADEMARK SECURITY AGREEMENT


                THIS  AGREEMENT  is made as of June  11,  1997,  by and  between
ENHANCED SYSTEMS,  INC., an Arizona corporation having a mailing address at 8300
East Raintree Drive, Scottsdale,  Arizona 85260 ("Debtor"), and GENERAL ELECTRIC
CAPITAL  CORPORATION,  a New York  corporation  having a mailing  address at 350
South Beverly Drive,  Suite 200,  Beverly Hills,  California 90212 (the "Secured
Party").

                               Statement of Facts
                               ------------------

                In connection with the financial  accommodations  to be extended
by the Secured Party to Vodavi  Communications  Systems,  Inc. (the  "Borrower")
under the Amended and Restated Credit  Agreement,  dated as of April 11, 1994 as
amended and restated  effective  as of June 11,  1997,  between the Borrower and
Secured Party (as the same may hereafter be amended,  restated,  supplemented or
otherwise modified from time to time, the "Credit Agreement"), Debtor has agreed
to  collaterally  assign  to the  Secured  Party  certain  trademark  rights  in
accordance with the terms of this Agreement.

                In  consideration  of the foregoing  premises and other good and
valuable consideration, Debtor hereby agrees with the Secured Party as follows:

                               Statement of Terms
                               ------------------

                Grant of Security  Interest.  To secure the  complete and timely
satisfaction of all of Debtor's obligations hereunder,  as well as to secure all
of the rights of the  Secured  Party  hereunder,  and to secure the  payment and
performance  of any and all  Obligations  (as such term is defined in the Credit
Agreement)  including  Debtor's  guarantee  thereof (all such Obligations  being
herein collectively called the "Secured  Obligations"),  Debtor hereby grants to
the  Secured  Party a present  and  continuing  security  interest in the entire
right,  title and interest of Debtor in and to the trademark  application(s) and
trademark(s)  listed on Schedule 1 attached hereto together with all goodwill of
Debtor's  business  relating thereto and all other assets of Debtor necessary to
produce the products for which such  applications will be or such trademarks are
used,  including  without  limitation  all proceeds  thereof (such as, by way of
example, license royalties and proceeds of infringement suits), the right to sue
for past, present and future  infringements,  all rights  corresponding  thereto
throughout the world and all renewals,  extensions  and other  proceeds  thereof
(collectively called the "Trademarks").

                Representations  and Warranties.  Debtor represents and warrants
that:

                The Trademarks are subsisting and have not been adjudged invalid
or unenforceable, in whole or in part;

                To the best of Debtor's  knowledge,  each of the  Trademarks  is
valid and
<PAGE>
enforceable;

                Debtor  is the  sole  and  exclusive  owner  of the  entire  and
unencumbered  right,  title and interest in and to each of the Trademarks,  free
and clear of any liens,  charges and encumbrances,  including without limitation
licenses  and  covenants  by Debtor  not to sue third  persons,  except  for any
Permitted Exceptions (as such term is defined in the Credit Agreement); and

                Debtor has the  unqualified  right to enter into this  Agreement
and perform its terms.

                No  Inconsistent  Licenses.  Debtor agrees that, so long as this
Agreement is in effect,  it will not enter into any agreement  (for  example,  a
license or assignment agreement) which is inconsistent with Debtor's obligations
under this Agreement, without the Secured Party's prior written consent.

                Event of  Default.  The  failure of the Debtor to perform any of
its  obligations   hereunder,   any  breach  in  any  material  respect  of  any
representation  or warranty of the Debtor herein, or the occurrence of any Event
of Default under (and as such term is defined in) the Credit Agreement will also
constitute a default by Debtor under this  Agreement  (herein  referred to as an
"Event of Default").

                Remedies on Default. If any Event of Default shall have occurred
and be continuing, the Secured Party shall have, in addition to all other rights
and remedies given it by this Agreement, those allowed by law and the rights and
remedies  of a secured  party  under the Code (as such  term is  defined  in the
Credit  Agreement) and,  without  limiting the generality of the foregoing,  the
Secured Party may  immediately,  without demand of performance and without other
notice or demand  whatsoever  to  Debtor,  sell at  public  or  private  sale or
otherwise  realize  upon,  the  whole  or  from  time to  time  any  part of the
Trademarks,  or any  interest  which the  Debtor  may have  therein  and,  after
deducting  from the proceeds of sale or other  disposition of the Trademarks all
expenses (including all reasonable expenses for legal services actually incurred
without giving effect to any statutory presumption),  shall apply the residue of
such proceeds toward the payment of the Secured  Obligations  (which application
shall  be made,  first,  to the  Secured  Party's  costs  and  expenses  of such
collection,  sale or other  disposition,  including  reasonable  attorney's fees
actually incurred without giving effect to any statutory  presumption,  and then
to the  payment of the other  Secured  Obligations  then due).  Debtor  shall be
liable for any deficiency remaining after the application of such proceeds.  Any
remainder of the proceeds after payment in full of the Secured Obligations shall
be paid over to the Debtor. If required by applicable law, notice of any sale or
other  disposition of the Trademarks  shall be given to Debtor at least ten (10)
days before the time of any intended public or private sale or other disposition
of the Trademarks is to be made,  which Debtor hereby agrees shall be reasonable
notice of such sale or other disposition.  At any such sale or other disposition
the Secured Party may, to the extent  permissible under applicable law, purchase
the whole or any part of the Trademarks  sold, free 
                                      -2-
<PAGE>
from any right of redemption on the part of Debtor, which right is hereby waived
and released.
                                      
                No Waiver.  No course of dealing  between Debtor and the Secured
Party, nor any failure to exercise, nor any delay in exercising,  on the part of
the Secured Party,  any right,  power or privilege  hereunder shall operate as a
waiver thereof;  nor shall any single or partial exercise of any right, power or
privilege  hereunder  preclude  any other or  further  exercise  thereof  or the
exercise of any other right, power or privilege.

                Severability.  The provisions of this Agreement are several, and
if any clause or provision shall be held invalid and  unenforceable  in whole or
in part in any  jurisdiction,  then such  invalidity or  unenforceability  shall
affect only such clause or provision, or part thereof, in such jurisdiction, and
shall  not  in  any  manner  affect  such  clause  or  provision  in  any  other
jurisdiction,  or any  other  clause  or  provision  of  this  Agreement  in any
jurisdiction.

                Modification.  This Agreement is subject to modification only by
a writing signed by the Debtor and the Secured Party.

                Benefit of Agreement. The benefits and burdens of this Agreement
shall inure to the benefit of and be binding upon the  respective  heirs,  legal
representatives, successors and assigns of the parties.

                Governing Law. The validity and interpretation of this Agreement
and the rights and  obligations  of the parties shall be governed by the laws of
the State of New York  (without  giving effect to its conflict of law rules) and
the United States of America.

                Terminology;  Headings.  All  singular  terms used herein  shall
include the plural and vice versa,  and all pronouns used herein shall be deemed
to cover all genders.  All section  headings used herein are for  convenience of
reference only and do not constitute a substantive part of this Agreement.

                Execution in Counterparts. This Agreement may be executed in any
number  of  counterparts,  each  of  which  counterparts  when so  executed  and
delivered,  shall be deemed to be an  original,  and all of which  counterparts,
taken together, shall constitute one and the same Agreement.

                Expenses;  Indemnity. Debtor will upon demand pay to the Secured
Party the amount of any and all expenses,  including reasonable  attorney's fees
and fees of  other  experts,  which  the  Secured  Party  may from  time to time
actually  incur  (and   calculated   without  giving  effect  to  any  statutory
presumption) in connection with (i) the  administration of this Agreement,  (ii)
the  preservation  of or the sale or other  disposition of or other  realization
upon any of the  Trademarks,  (iii) the  exercise or  enforcement  of any of the
rights of the  Secured  Party  hereunder  or (iv) the  failure  by the Debtor to
perform or observe any of 
                                      -3-
<PAGE>
the provisions hereof.  Debtor also hereby agrees to indemnify the Secured Party
and hold the  Secured  Party  harmless  from and against  any  liability,  loss,
damage,  suit,  action or  proceeding  ever  suffered or incurred by the Secured
Party as a result of (i)  Debtor's  failure to  observe,  perform  or  discharge
Debtor's duties  hereunder or (ii) the Secured Party's holding or  administering
this Agreement or its rights, titles or interests in the Trademarks, unless with
respect to any of the above,  the Secured Party is determined to have acted with
gross negligence or to have engaged in wilful misconduct. The obligations of the
Debtor under this paragraph 14 shall survive the termination of this Agreement.

                Security Agreement;  Intercreditor Agreement,  Entire Agreement;
Termination.  (a) The Secured Party also has a Lien in the Trademarks  under the
terms of the  Security  Agreement,  dated as of June 11,  1997,  executed by the
Debtor  in favor of the  Secured  Party  (the  "Security  Agreement"),  and this
Agreement is intended to supplement such Security Agreement, but in the event of
any inconsistency between the terms of this Agreement and those of such Security
Agreement,  the terms of such Security Agreement shall control,  and the Secured
Party may elect to pursue its rights and remedies with respect to the Trademarks
under either or both of this Agreement or such Security Agreement.

                (b)  This  Agreement,   together  with  all  other  instruments,
agreements and  certificates  executed by the parties in connection  herewith or
with reference hereto,  embodies the entire  understanding and agreement between
the parties  hereto with respect to the subject matter hereof and supersedes all
prior agreements,  understandings  and inducements,  whether express or implied,
oral or written.

                (c) This Agreement  shall terminate with, and in accordance with
the terms of, the Security  Agreement,  and all of the Secured Party's  security
interests hereunder shall be automatically  terminated and released on such date
(subject to reinstatement as provided in Section 11 of the Security Agreement).
                                       -4-
<PAGE>
                WITNESS the execution  hereof as of the day and year first above
written.

                                        DEBTOR:

                                        ENHANCED SYSTEMS, INC.


                                         By: /s/ Greg Roeper
                                            ------------------------------------
                                         Title: Secretary and Treasurer
                                               ---------------------------------

                                        SECURED PARTY:

                                        GENERAL ELECTRIC CAPITAL
                                        CORPORATION


                                         By: /s/ Timothy Morris
                                            ------------------------------------
                                         Title: Duly Authorized Signatory
                                               ---------------------------------
                                       -5-