Document:

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Exhibit 10.104c

THIS DEBENTURE,  AND THE SECURITIES INTO WHICH IT IS CONVERTIBLE  (COLLECTIVELY,
THE  "SECURITIES"),  HAVE NOT BEEN REGISTERED WITH THE UNITED STATES  SECURITIES
AND  EXCHANGE  COMMISSION  OR  THE  SECURITIES  COMMISSION  OF  ANY  STATE.  THE
SECURITIES ARE BEING OFFERED PURSUANT TO A SAFE HARBOR FROM  REGISTRATION  UNDER
REGULATION  D  PROMULGATED  UNDER THE  SECURITIES  ACT OF 1933,  AS AMENDED (THE
"ACT").  THE SECURITIES ARE  "RESTRICTED"  AND MAY NOT BE OFFERED OR SOLD UNLESS
THE  SECURITIES  ARE  REGISTERED  UNDER THE ACT,  PURSUANT  TO  REGULATION  D OR
PURSUANT TO AVAILABLE  EXEMPTIONS FROM THE REGISTRATION  REQUIREMENTS OF THE ACT
AND THE  COMPANY  WILL BE  PROVIDED  WITH  OPINION  OF  COUNSEL  OR  OTHER  SUCH
INFORMATION  AS IT MAY  REASONABLY  REQUIRE TO CONFIRM THAT SUCH  EXEMPTIONS ARE
AVAILABLE. FURTHER HEDGING TRANSACTIONS INVOLVING THE SECURITIES MAY NOT BE MADE
EXCEPT IN COMPLIANCE WITH THE ACT.

                                    DEBENTURE

                         VERTICAL COMPUTER SYSTEMS, INC.

                            0% CONVERTIBLE DEBENTURE

                               DUE APRIL 14, 2006

No.  ___                                                               $190,000

         This Debenture is issued by VERTICAL COMPUTER SYSTEMS, INC., a Delaware
corporation (the  "COMPANY"),  to Cornell Capital Partners LP (together with its
permitted  successors  and assigns,  the "HOLDER")  pursuant to exemptions  from
registration under the Securities Act of 1933, as amended.

                                   ARTICLE I.

         SECTION 1.01 PRINCIPAL AND INTEREST.  For value received,  on April 14,
2003,  the Company  hereby  promises to pay to the order of the Holder in lawful
money of the United  States of America and in  immediately  available  funds the
principal  sum  of  One  Hundred   Ninety   Thousand   Dollars  and  00/100  (US
$190,000.00),  together with interest on the unpaid  principal of this Debenture
at the rate of zero  percent  (0%) per year  (computed on the basis of a 365-day
year and the actual days elapsed) from the date of this Debenture until paid. At
the Company's option, the entire principal amount and all accrued interest shall
be either (a) paid to the Holder on the third  (3rd) year  anniversary  from the
date hereof or (b) converted in accordance with Section 1.02 herein.

         SECTION 1.02 OPTIONAL  CONVERSION.  Commencing one hundred eighty (180)
days after the date hereof,  the Holder is entitled,  at its option, to convert,
and sell on the same day,  at any time and from time to time,  until  payment in
full  of  this  Debenture,  all  or any  part  of the  principal  amount  of the
Debenture, plus accrued interest, into shares (the "CONVERSION SHARES") of the

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Company's  common stock, par value $0.00001 per SHARE ("COMMON  STOCK"),  at the
price per share (the "CONVERSION  PRICE") equal to one hundred percent (100%) of
the lowest closing bid price of the Common Stock as listed on a Principal Market
(as defined  herein),  as quoted by Bloomberg L.P. (the "CLOSING BID PRICE") for
the three (3) trading days immediately preceding the Conversion Date (as defined
herein). As used herein,  "PRINCIPAL MARKET" shall mean The National Association
of Securities Dealers Inc.'s  Over-The-Counter  Bulletin Board,  Nasdaq SmallCap
Market,  or  American  Stock  Exchange.  If the Common  Stock is not traded on a
Principal  Market,  the Closing Bid Price shall mean,  the reported  Closing Bid
Price  for the  Common  Stock,  as  furnished  by the  National  Association  of
Securities  Dealers,  Inc., for the applicable periods. No fraction of shares or
scrip  representing  fractions of shares will be issued on  conversion,  but the
number of shares  issuable  shall be  rounded to the  nearest  whole  share.  To
convert this Debenture,  the Holder hereof shall deliver written notice thereof,
substantially  in the form of EXHIBIT "A" to this  Debenture,  with  appropriate
insertions (the "CONVERSION NOTICE"), to the Company at its address as set forth
herein.  The date upon which the conversion  shall be effective (the "CONVERSION
DATE")  shall be  deemed  to be the date the  Company  receives  the  Conversion
Notice.

         SECTION 1.03 RESERVATION OF COMMON STOCK. The Company shall reserve and
keep available out of its authorized but unissued shares of Common Stock, solely
for the purpose of effecting the  conversion of this  Debenture,  such number of
shares of Common Stock as shall from time to time be  sufficient  to effect such
conversion, based upon the Conversion Price. If at any time the Company does not
have a sufficient number of Conversion Shares authorized and available, then the
Company shall call and hold a special meeting of its stockholders  within thirty
(30)  days of that  time  for the sole  purpose  of  increasing  the  number  of
authorized shares of Common Stock.

         SECTION 1.04 RIGHT OF REDEMPTION.  The Company at its option shall have
the right to redeem,  with thirty (30) business days advance written notice (the
"REDEMPTION NOTICE"), a portion or all outstanding  convertible  debenture.  The
redemption price shall be one hundred percent (100%) of the amount redeemed plus
accrued interest.

         SECTION 1.05 REGISTRATION  RIGHTS. The Company is obligated to register
the  resale of the  Conversion  Shares  under  the  Securities  Act of 1933,  as
amended,  pursuant to the terms of an Investor  Registration  Rights  Agreement,
between  the  Company  and the  Holder  of even  date  herewith  (the  "INVESTOR
REGISTRATION RIGHTS AGREEMENT").

         SECTION 1.06 PAYING AGENT AND  REGISTRAR.  Initially,  the Company will
act as paying  agent and  registrar.  The Company  may change any paying  agent,
registrar,  or  Company-registrar  by giving  the  Holder not less than ten (10)
business  days' written  notice of its election to do so,  specifying  the name,
address, telephone number and facsimile number of the paying agent or registrar.
The Company may act in any such capacity.

         SECTION 1.07 SUBORDINATED  NATURE OF DEBENTURE.  This Debenture and all
payments  hereon,  including  principal or interest,  shall be  subordinate  and
junior in right of payment to all accounts payable of the Company incurred in

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the  ordinary  course of business  and/or bank debt of the Company not to exceed
$190,000.

                                   ARTICLE II.

         SECTION 2.01 AMENDMENTS AND WAIVER OF DEFAULT. The Debenture may not be
amended with the consent of the Holder.  Notwithstanding the above,  without the
consent of the  Holder,  the  Debenture  may be  amended to cure any  ambiguity,
defect or inconsistency, to provide for assumption of the Company obligations to
the Holder or to make any change  that does not  adversely  affect the rights of
the Holder.

                                  ARTICLE III.

         SECTION  3.01  EVENTS OF  DEFAULT.  An Event of  Default  is defined as
follows:  (a) failure by the Company to pay amounts due hereunder within fifteen
(15) days of the date of maturity of this Debenture;  (b) failure by the Company
to comply with the terms of the Irrevocable Transfer Agent Instructions attached
to the Securities  Purchase Agreement of even date herewith entered into between
the  Company  and  the  Buyers  listed  on  SCHEDULE  I  attached  thereto  (the
"SECURITIES PURCHASE AGREEMENT"); (c) failure by the Company's transfer agent to
issue Common Stock to the Holder within ten (10) days of the  Company's  receipt
of the attached Notice of Conversion from Holder; (d) failure by the Company for
ten (10) days after notice to it to comply with any of its other  agreements  in
the  Debenture;  (e) events of  bankruptcy  or  insolvency;  (f) a breach by the
Company  of its  obligations  under the  Securities  Purchase  Agreement  or the
Investor  Registration Rights Agreement which is not cured by the Company within
ten (10) days after receipt of written notice thereof.

         SECTION 3.02 FAILURE TO ISSUE  UNRESTRICTED  COMMON STOCK. As indicated
in Article III Section  3.01, a breach by the Company of its  obligations  under
the Investor  Registration Rights Agreement shall be deemed an Event of Default,
which if not cured within ten (10) days,  shall  entitle the Holder  accelerated
full  repayment of all debentures  outstanding.  The Company  acknowledges  that
failure to honor a Notice of  Conversion  shall  cause  irreparable  harm to the
Holder.

         SECTION  3.03  AUTHORIZED  SHARES.  The  Company  shall take all action
reasonably  necessary  to at all times have  authorized,  and  reserved  for the
purpose of issuance, such number of shares of Common Stock as shall be necessary
to effect the issuance of the Conversion Shares. If at any time the Company does
not have  available  such  shares of Common  Stock as shall from time to time be
sufficient  to effect  the  conversion  of all of the  Conversion  Shares of the
Company shall call and hold a special meeting of the shareholders  within thirty
(30) days of such  occurrence,  for the sole purpose of increasing the number of
shares authorized.  The Company's management shall recommend to the shareholders
to vote in favor of increasing the number of shares of Common Stock  authorized.
Management  shall also vote all of its shares in favor of increasing  the number
of authorized shares of Common Stock.

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                                   ARTICLE IV.

         SECTION 4.01 RIGHTS AND TERMS OF CONVERSION.  This Debenture,  in whole
or in part,  may be converted at any time  following  the date of closing,  into
shares of Common Stock at a price equal to the Conversion  Price as described in
Section 1.02 above.

         SECTION  4.02  RE-ISSUANCE  OF  DEBENTURE.  When the  Holder  elects to
convert a part of the Debenture,  then the Company shall reissue a new Debenture
in the same form as this Debenture to reflect the new principal amount.

         SECTION 4.03  TERMINATION OF CONVERSION  RIGHTS.  The Holder's right to
convert the Debenture  into the Common Stock in accordance  with  paragraph 4.01
shall  terminate on the date that is the third (3rd) year  anniversary  from the
date hereof and this Debenture shall be automatically  converted on that date in
accordance  with  the  formula  set  forth  in  Section  4.01  hereof,  and  the
appropriate shares of Common Stock and amount of interest shall be issued to the
Holder.

         SECTION  4.04  RESTRICTION  ON SHORT SALE OF STOCK.  The Holder  hereby
acknowledges  and agrees that it shall not short sell the Common Stock except in
connection  with a  Conversion  Notice,  and  thereafter  only  such  number  of
Conversion Shares it receives with respect to such Conversion Notice.

                                   ARTICLE V.

         SECTION 5.01 ANTI-DILUTION.  In the event that the Company shall at any
time subdivide the  outstanding  shares of Common Stock,  or shall issue a stock
dividend  on the  outstanding  Common  Stock,  the  Conversion  Price in  effect
immediately  prior to such subdivision or the issuance of such dividend shall be
proportionately  decreased,  and in the event that the Company shall at any time
combine the outstanding  shares of Common Stock,  the Conversion Price in effect
immediately  prior  to such  combination  shall  be  proportionately  increased,
effective at the close of business on the date of such subdivision,  dividend or
combination as the case may be.

         SECTION 5.02 CONSENT OF HOLDER TO SELL  CAPITAL  STOCK.  Except for the
Equity Line of Credit  Agreement  dated the date hereof  between the Company and
Cornell Capital Partners,  LP. so long as any of the principal of or interest on
this Debenture  remains unpaid and  unconverted,  the Company shall not, without
the prior consent of the Holder, issue or sell (i) any Common Stock or Preferred
Stock without  consideration or for a consideration per share less than its fair
market value determined  immediately  prior to its issuance,  (ii) issue or sell
any common stock, preferred stock, warrant,  option, right,  contract,  call, or
other  security or instrument  granting the holder  thereof the right to acquire
Common Stock without  consideration  or for a consideration  per share less than
such  Common  Stock's  fair market  value  determined  immediately  prior to its
issuance,  (iii)  enter  into any  security  instrument  granting  the  holder a
security  interest  in any and all  assets  of the  Company  or  (iv)  file  any
registration statement on Form S-8.

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                                   ARTICLE VI.

         SECTION 6.01 NOTICE.  Notices regarding this Debenture shall be sent to
the  parties  at the  following  addresses,  unless a party  notifies  the other
parties, in writing, of a change of address:

If to the Company, to:           Vertical Computer Systems, Inc.
                                 6336 Wilshire Boulevard
                                 Los Angeles, CA 90048
                                 Attention:        Richard Wade
                                                   President
                                 Telephone:        (323) 658-4211
                                 Facsimile:        (322) 658-4214

With a copy to:                  Kirkpatrick & Lockhart LLP
                                 201 South Biscayne Boulevard - Suite 2000
                                 Miami, FL  33131-2399
                                 Attention:        Clayton E. Parker, Esq.
                                 Telephone:        (305) 539-3300
                                 Facsimile:        (305) 358-7095

If to the Holder:                Cornell Capital Partners LP
                                 101 Hudson Street - Suite 3606
                                 Jersey City, NJ 07302
                                 Attention:    Mark Angelo
                                 Telephone: (201) 985-8300
                                 Facsimile:  (201) 985-8266

With a copy to:                  Butler Gonzalez LLP
                                 1000 Stuyvesant Avenue - Suite 6
                                 Union, NJ 07083
                                 Attention:        David Gonzalez, Esq.
                                 Telephone:        (908) 810-8588
                                 Facsimile:        (908) 810-0973

         SECTION 6.02 GOVERNING  LAW. This Debenture  shall be deemed to be made
under  and  shall be  construed  in  accordance  with  the laws of the  State of
Delaware  without  giving effect to the  principals of conflict of laws thereof.
Each of the parties  consents to the  jurisdiction  of the U.S.  District  Court
sitting in the  District  of the State of New Jersey or the state  courts of the
State of New Jersey sitting in Hudson County,  New Jersey in connection with any
dispute  arising under this Debenture and hereby  waives,  to the maximum extent
permitted by law, any  objection,  including  any  objection  based on FORUM NON
CONVENIENS to the bringing of any such proceeding in such jurisdictions.

         SECTION 6.03  SEVERABILITY.  The invalidity of any of the provisions of
this  Debenture  shall  not  invalidate  or  otherwise  affect  any of the other
provisions of this Debenture, which shall remain in full force and effect.

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         SECTION 6.04 ENTIRE AGREEMENT AND AMENDMENTS. This Debenture represents
the entire  agreement  between  the parties  hereto with  respect to the subject
matter  hereof  and there are no  representations,  warranties  or  commitments,
except as set forth herein.  This Debenture may be amended only by an instrument
in writing executed by the parties hereto.

         SECTION 6.05  COUNTERPARTS.  This Debenture may be executed in multiple
counterparts,  each of which  shall be an  original,  but all of which  shall be
deemed to constitute on instrument.

         IN WITNESS  WHEREOF,  with the intent to be legally bound  hereby,  the
Company as executed this Debenture as of the date first written above.

                                       VERTICAL COMPUTER SYSTEMS, INC.

                                       By:
                                       ---------------------------------
                                       Name:    Richard S. Wade
                                       Title:   President

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                                   EXHIBIT "A"

                              NOTICE OF CONVERSION

           (TO BE EXECUTED BY THE HOLDER IN ORDER TO CONVERT THE NOTE)

TO:

         The undersigned hereby irrevocably elects to convert $______________ of
the  principal  amount of the above  Debenture  into  Shares of Common  Stock of
Vertical Computer Systems,  Inc., according to the conditions stated therein, as
of the Conversion Date written below.

CONVERSION DATE:
                                       --------------------------------------
APPLICABLE CONVERSION PRICE:
                                       --------------------------------------
SIGNATURE:
                                       --------------------------------------
NAME:
                                       --------------------------------------
ADDRESS:
                                       --------------------------------------
AMOUNT TO BE CONVERTED:  $
                                       --------------------------------------
AMOUNT OF DEBENTURE UNCONVERTED: $
                                       --------------------------------------
CONVERSION PRICE PER SHARE: $
                                       --------------------------------------
NUMBER OF SHARES OF COMMON STOCK TO BE
ISSUED:
                                       --------------------------------------
PLEASE ISSUE THE SHARES OF COMMON STOCK
IN THE FOLLOWING NAME AND TO THE
FOLLOWING ADDRESS:
                                       --------------------------------------
ISSUE TO:
                                       --------------------------------------
AUTHORIZED SIGNATURE:
                                       --------------------------------------
NAME:
                                       --------------------------------------
TITLE:
                                       --------------------------------------
PHONE NUMBER:
                                       --------------------------------------
BROKER DTC PARTICIPANT CODE:
                                       --------------------------------------
ACCOUNT NUMBER:
                                       --------------------------------------

                                       A-1<PAGE>

Exhibit 10.105a
                                 April 14, 2003

Vasu Vijay
3109 Wyndmere Drive
Richardson, TX 75082

RE: SERVICES 2003-2004

April 14, 2002

This letter will confirm our mutual  understanding of January 15, 2003 regarding
our  agreement  whereby  you  will  assist  Vertical   Computer  Systems,   Inc.
("Vertical").  You  and  Vertical  confirm  and  agree  that,  subject  to  your
professional  commitments,  you will assist and provide  Vertical with strategy,
sales, marketing, and administration services upon Vertical's reasonable request
for a period of 12 months.

Vertical  agrees to extend your warrants and stock options issued to you in 2001
for one (1) year and shall also issue 1,100,000  shares of Vertical common stock
to you within 90 days. If the  foregoing is  acceptable  to you,  please sign as
provided below.

Very truly yours,

Richard Wade
President/CEO
Vertical Computer Systems, Inc.

ACCEPTED AND AGREED:

Vasu Vijay, an individual

---------------------------
Vasu Vijay, an individual

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