Document:

EXHIBIT 10.11

                                 LOAN AGREEMENT

     THIS LOAN  AGREEMENT  ("Agreement")  is made and entered into as of October
31, 2001, by and between TEKELEC,  a California  corporation  ("Borrower"),  and
UNION BANK OF CALIFORNIA, N.A., a national banking association ("Bank").

     SECTION 1. THE LOAN

     1.1 The Revolving  Loan. Bank will loan to Borrower an amount not to exceed
Twenty  Million  Dollars  ($20,000,000)  outstanding in the aggregate at any one
time (the "Revolving Loan"). Borrower may borrow, repay and reborrow all or part
of the Revolving Loan in amounts of not less than Five Hundred  Thousand Dollars
($500,000) in accordance  with the terms of the Revolving  Note (as such term is
defined herein below).  All borrowings of the Revolving Loan must be made before
October 31, 2002 (the  "Revolving  Loan  Termination  Date"),  at which time all
unpaid  principal of and accrued but unpaid interest on the Revolving Loan shall
be due and payable.  The Revolving Loan shall be evidenced by a promissory  note
(the  "Revolving  Note")  on the  standard  form  used by Bank to  evidence  its
commercial  loans.  Bank shall enter each amount  borrowed  and repaid in Bank's
records and such entries shall be deemed to be the amount of the Revolving  Loan
outstanding.  The omission of Bank to make any such entries  shall not discharge
Borrower of its obligation to repay in full with interest all amounts borrowed.

          1.1.1 The L/C Line. Bank shall issue, for the account of Borrower, one
     or more irrevocable  commercial or standby letters of credit (individually,
     an "L/C" and collectively,  the "L/Cs") and in the case of commercial L/Cs,
     calling for drafts at sight  covering the  importation or purchase of goods
     required in the normal course of business.  Each L/C shall be drawn on such
     terms and conditions as are acceptable to Bank and shall be governed by the
     terms of (and  Borrower  agrees to execute)  Bank's  standard  form for L/C
     application and reimbursement  agreement. The aggregate amount available to
     be drawn  under all  outstanding  L/Cs and the  aggregate  amount of unpaid
     reimbursement  obligations  under drawn L/Cs shall not exceed Five  Million
     Dollars  ($5,000,000)  and shall  reduce,  dollar for  dollar,  the maximum
     amount  available under the Revolving Loan. No L/C shall have an expiration
     date  more  than 365 days from its date of  issuance.  No L/C shall  expire
     after the Revolving Loan Termination Date.

     1.2  Terminology.  As used  herein,  the  following  terms  shall  have the
following meanings:

          (a) "Loan"  shall  mean,  collectively,  all of the credit  facilities
     described above.

          (b)  "Loan  Documents"  shall  mean  all  documents,  instruments  and
     agreements executed in connection with this Agreement.

          (c) "Note"  shall  mean,  collectively,  all of the  promissory  notes
     described above.

     1.3 Purpose of Loan.  The proceeds of the Revolving  Loan shall be used for
Borrower's general corporate purposes and working capital.

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                                                                   EXHIBIT 10.11

     1.4 Interest.  The unpaid principal balance of the Loan shall bear interest
at the rate or rates provided in the Note and selected by Borrower. The Loan may
be prepaid in full or in part only in accordance  with the terms of the Note and
any such prepayment shall be subject to the prepayment fee provided for therein.

     1.5     Commitment/Documentation     Fee.     Borrower    shall    pay    a
commitment/documen-tation  fee to  Bank  in the sum of  Fifty  Thousand  Dollars
($50,000) on or before October 31, 2001. In the event that Borrower does not pay
such commitment fee to Bank before October 31, 2001, then Bank shall  autocharge
Borrower's operating account with Bank for the amount of such commitment fee. No
portion of such commitment fee shall be reimbursable.

     1.6 Unused  Commitment  Fee.  On the last  calendar  day of the third month
following the  execution of this  Agreement and on the last calendar day of each
three (3) month period  thereafter until the Revolving Loan Termination Date, or
on the  earlier  termination  of the Loan,  Borrower  shall pay to Bank a fee of
thirty one-hundredths  percent (.30%) per annum on the average unused portion of
the Loan for the  preceding  three (3) month  period,  computed  on the basis of
actual days elapsed of a year of 360 days.

     1.7 Balances.  Borrower shall maintain its major  depository  accounts with
Bank until the Note and all other sums payable  pursuant to this  Agreement have
been paid in full.

     1.8 Disbursement.  Bank shall disburse the proceeds of the Loan as provided
for in Bank's standard form Authorization to Disburse executed by Borrower.

     1.9 Security.  Prior to any  disbursement of the Loan,  Borrower shall have
executed  a  security  agreement,  on  Bank's  standard  form,  and a  financing
statement,  suitable  for filing in the office of the  Secretary of State of the
State of California and any other state  designated by Bank,  granting to Bank a
first priority security interest in such of Borrower's  property as is described
in said security agreement.  Exceptions to Bank's first priority,  are permitted
as shown in Exhibit A to this Agreement.  At Bank's request,  Borrower will also
obtain executed  landlord's and mortgagee's  waivers on Bank's form covering all
of Borrower's property located on leased or encumbered real property.

     1.10 Controlling  Document.  In the event of any inconsistency  between the
terms of this  Agreement  and the Note or any of the other Loan  Documents,  the
terms of the Note or such other Loan  Documents  will  prevail over the terms of
this Agreement.

     SECTION 2. CONDITIONS PRECEDENT

     Bank shall not be  obligated to disburse all or any portion of the proceeds
of the Loan unless at or prior to the time for the making of such  disbursement,
the following conditions have been fulfilled to Bank's satisfaction:

     2.1  Compliance.  Borrower shall have performed and complied with all terms
and conditions required by this Agreement to be performed or complied with prior
to or at the date of the making of such disbursement and shall have executed and
delivered to Bank the Note and the other Loan Documents.

     2.2 Guaranties. IEX Corporation, a Nevada corporation ("Guarantor"),  shall
have  executed and  delivered  to Bank a continuing  guaranty in form and amount
satisfactory to Bank.

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                                                                   EXHIBIT 10.11

In addition, any and all future domestic subsidiaries of Borrower shall promptly
execute  and  deliver  to  Bank   continuing   guaranties  in  form  and  amount
satisfactory to Bank.

     2.3 Borrowing Resolution.  Borrower shall have provided Bank with certified
copies of  resolutions  duly  adopted  by the board of  directors  of  Borrower,
authorizing  the execution,  delivery and  performance of this Agreement and the
Loan  Documents.  Such  resolutions  shall also  designate  the  persons who are
authorized to act on Borrower's  behalf in connection with this Agreement and to
do the things required of Borrower pursuant to this Agreement.

     2.4  Termination  Statements.  Borrower shall have provided Bank with UCC-3
termination  statements executed by such secured creditors as may be required by
Bank suitable for filing with the Secretary of State in each state designated by
Bank.

     2.5  Continuing  Compliance.  At the time any  disbursement  is to be made,
there shall not exist any event,  condition or act which constitutes an Event of
Default under Section 6 hereof or any event, condition or act which with notice,
lapse of time or both would  constitute an Event of default;  nor shall there be
any such event,  condition, or act immediately after the disbursement were it to
be made.

     SECTION 3. REPRESENTATIONS AND WARRANTIES

     Borrower represents and warrants that:

     3.1 Business  Activity.  The principal  business of Borrower is the design,
manufacture,  and support of network  system  products,  diagnostic  systems and
selected service applications for telecommunications networks and call centers.

     3.2 Affiliates and  Subsidiaries.  Borrower's  affiliates and  subsidiaries
(those entities in which Borrower has either a controlling  interest or at least
a 25%  ownership  interest)  and their  addresses,  and the names of  Borrower's
principal  shareholders,  are as provided on a schedule  delivered to Bank on or
before the date of this Agreement.

     3.3 Authority to Borrow.  The execution,  delivery and  performance of this
Agreement, the Note and all other Loan Documents are not in contravention of any
of the terms of any  indenture,  agreement or undertaking to which Borrower is a
party or by which it or any of its property is bound or affected.

     3.4  Financial  Statements.  The  financial  statements of Borrower and its
subsidiaries  on Form 10Q,  including both a consolidated  balance sheet at June
30,  2001,  together  with  supporting  schedules,  and  a  consolidated  income
statement  for the three (3) months ended June 30, 2001,  have  heretofore  been
furnished to Bank, and are true and complete and fairly  represent the financial
condition of Borrower and its  subsidiaries  during the period covered  thereby.
Since June 30, 2001,  there has been no material adverse change in the financial
condition or operations of Borrower or any of its subsidiaries.

     3.5  Title.  Except  for  assets  which  may have been  disposed  of in the
ordinary  course  of  business,  Borrower  and its  subsidiaries  have  good and
marketable title to all of the property reflected in the financial statements of
Borrower and its subsidiaries  delivered to Bank and to all property acquired by
Borrower and its subsidiaries since the date of such financial statements,  free
and clear of all liens,  encumbrances,  security  interests  and adverse  claims
(collectively,

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                                                                   EXHIBIT 10.11

"Liens"),  except for Liens incurred in the ordinary course of business which do
not result in a material  adverse effect on the financial  condition of Borrower
or any of its subsidiaries.

     3.6 Litigation.  There is no litigation or proceeding pending or threatened
against  Borrower  or any  of its  subsidiaries,  or  any  of  their  respective
properties, which is reasonably likely to result in a material adverse effect on
the  financial  condition,  property  or  business  of  Borrower  or  any of its
subsidiaries  or  result  in  liability  in  excess  of  Borrower's  or any such
subsidiary's insurance coverage.

     3.7  Default.  Borrower  is not now in default in the payment of any of its
material  obligations,  and  there  exists  no  event,  condition  or act  which
constitutes  an Event of Default under Section 6 hereof and no condition,  event
or act which with notice or lapse of time, or both, would constitute an Event of
Default.

     3.8 Organization. Borrower is duly organized and existing under the laws of
the  State  of  California,  and has the  power  and  authority  to carry on the
business in which it is engaged and/or proposes to engage.

     3.9  Power.  Borrower  has the  power  and  authority  to enter  into  this
Agreement  and to  execute  and  deliver  the  Note  and all of the  other  Loan
Documents.

     3.10  Authorization.  This  Agreement  and  all  things  required  by  this
Agreement  have  been  duly  authorized  by all  requisite  corporate  action of
Borrower.

     3.11 Qualification.  Borrower is duly qualified and in good standing in any
jurisdiction where such qualification is required.

     3.12  Compliance  With Laws.  Borrower is in compliance with all applicable
laws,  rules,  ordinances and regulations which materially affect the operations
or financial condition of Borrower.

     3.13 ERISA.  All defined  benefit pension plans (as such term is defined in
the Employee  Retirement  Income Security Act of 1974, as amended  ("ERISA")) of
Borrower meet, as of the date hereof,  the minimum funding  standards of Section
302 of ERISA,  and no Reportable  Event or Prohibited  Transaction as defined in
ERISA has occurred with respect to any such plan.

     3.14  Regulation  U. No action  has been taken or is  currently  planned by
Borrower, or any agent acting on its behalf, which would cause this Agreement or
the  Note to  violate  Regulation  U or any  other  regulation  of the  Board of
Governors  of the  Federal  Reserve  System or to  violate  the  Securities  and
Exchange Act of 1934, in each case as in effect now or as the same may hereafter
be in effect.  Borrower is not engaged in the business of  extending  credit for
the purpose of  purchasing  or  carrying  margin  stock as one of its  important
activities  and  none of the  proceeds  of the  Loan  will be used  directly  or
indirectly for such purpose.

     3.15 "Senior Indebtedness" as Defined in the Indenture Dated as of November
2,  1999  between  Borrower  and  Bankers  Trust  Company   ("indenture").   The
obligations  and  liabilities of Borrower to Bank  thereunder  shall  constitute
"senior Indebtedness," as such term is defined in the Indenture.

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                                                                   EXHIBIT 10.11

     3.16  Continuing  Representations.  These  representations  shall  be  con-
sidered  to have been made again at and as of the date of each  disbursement  of
the Loan and shall be true and correct as of such date or dates.

     SECTION 4. AFFIRMATIVE COVENANTS

     Until the Note and all sums payable pursuant to this Agreement and the Loan
Documents  have been paid in full,  unless Bank  otherwise  consents in writing,
Borrower agrees that:

     4.1 Use of Proceeds.  Borrower will use the proceeds of the Revolving  Loan
only as provided in subsection 1.3 hereof.

     4.2 Payment of  Obligations.  Borrower will pay and discharge  promptly all
taxes,  assessments and other governmental  charges and claims levied or imposed
upon it or its property, or any part thereof;  provided,  however, that Borrower
shall  have the right in good  faith to  contest  any such  taxes,  assessments,
charges or claims and,  pending the outcome of such contest,  to delay or refuse
payment thereof  provided that adequately  funded reserves are established by it
to pay and discharge any such taxes, assessments, charges and claims.

     4.3  Maintenance  of  Existence.  Borrower  will  maintain and preserve its
existence and assets and all rights,  franchises,  licenses and other  authority
necessary  for the conduct of its  business  and will  maintain and preserve its
property,  equipment and  facilities in good order,  condition and repair.  Bank
may, at reasonable times, visit and inspect any of the properties of Borrower.

     4.4 Records. Borrower will keep and maintain full and accurate accounts and
records of its operations according to generally accepted accounting  principles
and will permit Bank to have access thereto, to make examination and photocopies
thereof, and to make audits during regular business hours. Costs for such audits
shall be paid by Borrower.

     4.5 Information Furnished. Borrower will furnish to Bank:

          (a)  Within  forty-five  (45)  days  after  the  close of each  fiscal
     quarter,  except for the final  fiscal  quarter of each  fiscal  year,  the
     unaudited,  consolidated  balance sheet of Borrower and its subsidiaries on
     Form 10Q as of the close of such  fiscal  quarter,  including  at least the
     unaudited,  consolidated  income and expense  statement of Borrower and its
     subsidiaries with supportive schedules for such fiscal quarter, prepared in
     accordance with generally accepted accounting principles;

          (b)  Within  one  hundred  twenty  (120)  days after the close of each
     fiscal  year, a copy of its  statement of financial  condition on Form 10K,
     including  at least the  consolidated  balance  sheet of  Borrower  and its
     subsidiaries  as of the  close of such  fiscal  year  and the  consolidated
     income and expense  statement  of Borrower  and its  subsidiaries  for such
     fiscal  year,  examined  and  prepared on an audited  basis by  independent
     certified   public   accountants   selected  by  Borrower  and   reasonably
     satisfactory  to Bank, in accordance  with  generally  accepted  accounting
     principles  applied on a basis  consistent with that of the previous fiscal
     year;

          (c) Such  other  financial  statements  and  information  relating  to
     Borrower and it  subsidiaries  as Bank may reasonably  request from time to
     time;

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                                                                   EXHIBIT 10.11

          (d) In connection with each financial statement provided hereunder,  a
     statement executed by a responsible officer of Borrower, certifying that no
     Event of Default has  occurred and no event exists which with notice or the
     lapse of time, or both, would result in an Event of Default hereunder;

          (e) In  connection  with  each  fiscal  year  end  statement  required
     hereunder, any management letter of Borrower's independent certified public
     accountants as requested by Bank;

          (f) Within forty-five (45) days after the close of each fiscal quarter
     and within  one-hundred  twenty  (120) days after each  fiscal  year end, a
     certification  of  compliance  with all  covenants  under  this  Agreement,
     executed by Borrower's  chief  financial  officer or other duly  authorized
     officer of Borrower, in form acceptable to Bank;

          (g) Prompt  written  notice to Bank of all Events of Default under any
     of the terms or  provisions  of this  Agreement  or of any event of default
     under any other agreement,  contract,  document or instrument entered into,
     or to be entered into,  with Bank; and of any litigation  which, if decided
     adversely  to  Borrower or any of its  subsidiaries,  would have a material
     adverse  effect  on  the  financial  condition  of  Borrower  or any of its
     subsidiaries;  and of any other  matter which has resulted in, or is likely
     to result in, a  material  adverse  change in the  financial  condition  or
     operations of Borrower or any of its subsidiaries; and

          (h) When  possible,  prior  written  notice to Bank of any  changes in
     Borrower's  chief  executive  officer,  chief  financial  officer,   senior
     director of finance or treasurer (or prompt  written  notice  following any
     unanticipated  and unexpected  change in any of such officers);  Borrower's
     name; or the location of Borrower's assets,  principal place of business or
     chief executive office.

     4.6 Liquid Assets. Borrower will at all times maintain Liquid Assets of not
less than Forty Million Dollars ($40,000,000).  As used herein, the term "Liquid
Assets" shall mean cash and  marketable  securities  (short-term  and long-term)
owned by Borrower.

     4.7 Consolidated  Total Debt to Consolidated  Tangible Net Worth.  Borrower
will maintain at all times a ratio of  Consolidated  Total Debt to  Consolidated
Tangible  Net Worth of not greater  than 1.0 to 1.0 as at the end of each fiscal
quarter. As used in this Agreement, "Total Debt" shall mean total liabilities of
Borrower or any of its  subsidiaries as defined by GAAP on a consolidated  basis
less  indebtedness of Borrower or any of its subsidiaries  subordinated to Bank.
"Consolidated  Tangible  Net Worth" shall mean the net worth of Borrower and its
subsidiaries,  increased by indebtedness of Borrower or any of its  subsidiaries
subordinated  to Bank and  decreased  by patents,  licenses,  trademarks,  trade
names,  goodwill and other similar  intangible  assets of Borrower or any of its
subsidiaries, organizational expenses and monies due from affiliates to Borrower
or any of its subsidiaries  (including the officers,  shareholders and directors
of any thereof).

     4.8  Consolidated   Rolling-Four  Quarter  EBITDA.  Borrower  will  achieve
consolidated  rolling-four quarter EBITDA of not less than Forty Million Dollars
($40,000,000)  for  each  fiscal  quarter.  "Consolidated  Rolling-Four  Quarter
EBITDA"  shall mean the net profit after taxes of Borrower and its  subsidiaries
for the  preceding  four (4) fiscal  quarters,  plus  interest  expense,  taxes,
depreciation  and  amortization for Borrower or any of its subsidiaries for such
four (4) fiscal quarters,  less interest income of Borrower and its subsidiaries
for such four (4) fiscal quarters.

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                                                                   EXHIBIT 10.11

     4.9 Insurance.  Borrower will keep all of its insurable  property,  whether
real,  personal or mixed,  insured by companies and in amounts  approved by Bank
against  fire and such  other  risks,  and in such  amounts,  as is  customarily
obtained  by  companies   conducting  similar  business  with  respect  to  like
properties.  Borrower will furnish to Bank statements of its insurance coverage,
will promptly furnish other or additional insurance deemed necessary by and upon
request of Bank to the extent that such  insurance  may be available  and hereby
assigns to Bank, as security for Borrower's obligations to Bank, the proceeds of
any such  insurance.  Prior to any  disbursement of the Loan, Bank will be named
loss payee on all policies  insuring  collateral and such policies shall require
at least ten (10) days' written  notice to Bank before any policy may be altered
or cancelled.  Borrower will maintain adequate worker's  compensation  insurance
and adequate insurance against liability for damage to persons or property.

     4.10 Additional Requirements.  Borrower will promptly, upon demand by Bank,
take  such  further  action  and  execute  all  such  additional  documents  and
instruments  in  connection  with  this  Agreement  as  Bank  in its  reasonable
discretion deems necessary, and promptly supply Bank with such other information
concerning the affairs of Borrower and its subsidiaries as Bank may request from
time to time.

     4.11  Litigation  and Attorneys'  Fees.  Borrower will pay promptly to Bank
upon  demand,  reasonable  attorneys'  fees  (including  but not  limited to the
reasonable  estimate of the  allocated  costs and  expenses  of  in-house  legal
counsel and staff) and all costs and other  expenses paid or incurred by Bank in
collecting, modifying or compromising the Loan or in enforcing or exercising its
rights or remedies  created by, connected with or provided for in this Agreement
or any of the Loan Documents, whether or not an arbitration,  judicial action or
other  proceeding  is  commenced.  If such  proceeding  is  commenced,  only the
prevailing party shall be entitled to attorneys' fees and court costs.

     4.12 Bank  Expenses.  Borrower  will pay or  reimburse  Bank for all costs,
expenses and fees  incurred by Bank in  preparing  and  documenting  any and all
amendments and modifications to this Agreement and the Loan Documents, including
but not limited to attorneys'  fees,  including the  reasonable  estimate of the
allocated costs and expenses of in-house legal counsel and staff.

     4.13 Reports Under Pension Plans. Borrower will furnish to Bank, as soon as
possible and in any event within  fifteen (15) days after  Borrower knows or has
reason to know that any event or condition  with respect to any defined  benefit
pension plans of Borrower  described in subsection  3.13 hereof has occurred,  a
statement  of an  authorized  officer  of  Borrower  describing  such  event  or
condition and the action,  if any, which Borrower  proposes to take with respect
thereto.

     SECTION 5. NEGATIVE COVENANTS

     Until the Note and all other sums payable  pursuant to this  Agreement  and
the Loan  Documents have been paid in full,  unless Bank  otherwise  consents in
writing, Borrower agrees that:

     5.1 Liens.  Borrower will not, and will not permit any of its  subsidiaries
to create,  assume or permit to exist any Lien on any of its  property,  whether
real, personal or mixed, now owned or hereafter acquired,  or upon the income or
profits thereof, except for (a) Liens, if any, in

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                                                                   EXHIBIT 10.11

favor of Bank,  (b)  Liens  incurred  in the  ordinary  course  of  business  in
connection  with  worker's  compensation,   unemployment  insurance  or  similar
legislation,  (c) Liens created to secure  indebtedness  permitted by subsection
5.2(c)  hereof,  which is  incurred  solely  for the  purpose of  financing  the
acquisition of such assets and incurred at the time of  acquisition,  so long as
each such Lien shall at all times be  confined  solely to the asset or assets so
acquired (and proceeds  thereof),  and refinancings  thereof so long as any such
Lien  remains  solely  on the asset or assets  acquired  and the  amount of such
indebtedness  related  thereto  is not  increased,  (d) minor  encumbrances  and
easements on real property  which do not affect its market value,  (e) Liens for
taxes not  delinquent  and for taxes and other  items  being  contested  in good
faith, (f) Liens on personal property in existence on the date of this Agreement
and (g) Liens in respect of judgments or awards for which appeals or proceedings
for review are being prosecuted and in respect of which a stay of execution upon
any such appeal or proceeding for review shall have been secured,  provided that
(i) Borrower or such subsidiary  shall have  established  adequate  reserves for
such  judgments or awards,  (ii) such judgments or awards shall be fully insured
and the  insurer  shall not have denied  coverage,  or (iii) such  judgments  or
awards shall have been bonded to the satisfaction of Bank.

     5.2 Indebtedness.  Borrower will not sell,  discount or otherwise  transfer
any account  receivable or any note,  draft or other  evidence of  indebtedness,
except to Bank or except to a financial institution at face value for deposit or
collection purposes only and without any fee other than fees normally charged by
the financial institution for deposit or collection services. Borrower will not,
nor shall it permit any subsidiary to create,  assume, incur or otherwise become
or remain  obligated  in respect of, or permit to be  outstanding,  or suffer to
exist any  indebtedness,  except (a)  indebtedness  under this Agreement and the
Loan Documents,  (b) accounts  payable and accrued  liabilities  incurred in the
ordinary  course  of  business,  (c)  indebtedness,   including  in  respect  of
capitalized lease obligations,  incurred to purchase, or to finance the purchase
of,  assets which  constitute  property,  plant and  equipment,  in an aggregate
principal  amount  not in  excess  of Five  Million  Dollars  ($5,000,000),  (d)
interest hedging  obligations under interest hedge agreements  entered into with
Bank or any other financial institution,  (e) obligations under foreign exchange
hedge agreements entered into with Bank or any other financial institution,  (f)
indebtedness  existing on the date of this Agreement  (including overdraft lines
for Japanese subsidiary),  or permitted to be incurred under agreements existing
on the date of this Agreement, including renewals, replacements and refinancings
(but no  increases)  thereof,  (g)  indebtedness  in respect of  endorsement  of
negotiable  instruments  in the ordinary  course of business,  (h)  indebtedness
owing to Borrower or any of its subsidiaries by any subsidiary of Borrower which
has executed a continuing  guaranty in favor of Bank as provided for herein, and
(i) guaranties by  subsidiaries of Borrower of indebtedness of Borrower or other
subsidiaries  of  Borrower,  to  the  extent  such  underlying  indebtedness  is
permitted hereunder,

     5.3 Sale of  Assets.  Borrower  will not,  and will not  permit  any of its
subsidiaries  to,  sell,  lease,  transfer or  otherwise  dispose of, any of its
assets except (a) inventory in the ordinary course of business,  (b) obsolete or
worn-out  assets and (c) provided that no Event of Default or event which,  with
notice or lapse of time,  or both,  would become an Event of Default,  exists or
would exist immediately prior to or after giving effect thereto,  sales of other
assets,  the fair market  value of which  shall not exceed One  Million  Dollars
($1,000,000) in aggregate amount during any fiscal year.

     5.4  Liquidation  or Merger.  Borrower will not, and will not permit any of
its subsidiaries to, at any time:

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                                                                   EXHIBIT 10.11

          (a)  liquidate  or  dissolve  itself  (or suffer  any  liquidation  or
     dissolution) or otherwise wind up, except that (i) a subsidiary of Borrower
     may liquidate or dissolve into Borrower,  (ii) a subsidiary of Borrower may
     liquidate  or  dissolve  into  a  domestic  subsidiary,   (iii)  a  foreign
     subsidiary  of Borrower  may  liquidate  or dissolve  into  another  direct
     foreign subsidiary of Borrower or a domestic subsidiary; or

          (b) enter into any merger or consolidation  unless (i) with respect to
     a  merger  or  consolidation  involving  Borrower,  Borrower  shall  be the
     surviving  corporation,  or if  the  merger  or  consolidation  involves  a
     subsidiary  of Borrower  and not  Borrower,  such  subsidiary  shall be the
     surviving corporation, in each case other than solely to effect a change of
     the jurisdiction of  incorporation of Borrower or any of its  subsidiaries,
     (ii) such transaction  shall not be utilized to circumvent  compliance with
     any term or provision  hereof,  (iii) no Event of Default  shall then be in
     existence  or occur as a result of such  transaction  and (iv) no  domestic
     subsidiary  shall be  permitted  to enter into any merger or  consolidation
     with a foreign  subsidiary  unless such  domestic  subsidiary  shall be the
     surviving corporation.

     5.5  Acquisitions.  Borrower  will not,  and shall  not  permit  any of its
subsidiaries  to purchase all or any portion of the stock,  equity  interests or
assets of any person or entity;  provided,  however, that Borrower or any of its
subsidiaries may make any acquisition so long as (a) the board of the company to
be acquired has approved the transaction; (b) the company to be acquired is in a
line of  business  similar to  Borrower's;  (c)  immediately  prior to and after
giving effect to the proposed  acquisition as evidenced by a proforma compliance
certificate  provided  to Bank  there  shall  not  exist  an  Event  of  Default
hereunder,  (d) the  consideration  payable  or to be paid by  Borrower  or such
subsidiary  for  such   acquisition  does  not  exceed  Thirty  Million  Dollars
($30,000,000)  per single  acquisition or Ninety Million  Dollars  ($90,000,000)
during any 12-month  period for more than one acquisition and (e) in the case of
any proposed  acquisition  Borrower  shall have provided Bank with the pro forma
financial  statements of Borrower and its subsidiaries  (including the person or
entity so acquired) prior to the consummation of such acquisition.  Acquisitions
financed  entirely with preferred and common stock (of which no more than 40% of
the  purchase  price shall be preferred  equity) can be  completed  without Bank
approval.  The Revolving Line shall not be used to finance  acquisitions without
prior Bank approval.

     5.6 Investments.  Borrower will not, and will not permit any subsidiary to,
make any  investment,  except  that  Borrower  and any of its  subsidiaries  may
purchase or otherwise acquire and own (a) cash, cash equivalents, and marketable
securities,  (b)  accounts  receivable  and notes  receivable  that arise in the
ordinary course of business and are payable on standard  terms,  (c) investments
in  existence  on the date of this  Agreement,  (d)  investments  in the form of
interest hedge agreements permitted by subsection 5.2(d) hereof, (e) investments
consisting  of advances to  employees in the  ordinary  course of business,  (f)
investments in existing domestic subsidiaries of Borrower,  (g) investments made
after the date of this  Agreement  in foreign  subsidiaries  of  Borrower  in an
aggregate amount not to exceed Five Million Dollars  ($5,000,000),  (h) minority
investments  in other  persons or  entities,  provided  that each such person or
entity is engaged  primarily in the business of the manufacture and distribution
of software and hardware for computer networking and activities directly related
thereto  and  (i)  other   investments   not  to  exceed  Five  Million  Dollars
($5,000,000) in the aggregate at any time outstanding.

     5.7  Restricted  Payments.  Borrower shall not, and shall not permit any of
its subsidiaries to, directly or indirectly, declare, pay or make any Restricted
Payments  except for (a)  Dividends  payable to  stockholders  of Borrower,  (b)
Dividends  payable by a  subsidiary  of  Borrower  to  Borrower  or to  domestic
subsidiary of

<PAGE>

                                                                   EXHIBIT 10.11

Borrower, (c) provided that no Event of Default exists or will exist immediately
prior to or after  giving  effect to such  Restricted  Payment,  acquisition  of
shares of capital stock  pursuant to employee stock purchase plans or agreements
to repurchase  directors'  qualifying  shares not to exceed One Million  Dollars
($1,000,000)  in aggregate  amount during any fiscal year, and (d) provided that
no Event of Default  exists or will exist  immediately  prior to or after giving
effect to such Restricted  Payment and provided that Borrower provides Bank with
a minimum seven (7) days written notice,  redemption of Borrower's  $135,000,000
3.25% Convertible  Subordinated  Discount Notes provided that the cash principal
and interest  payment for such redemption does not exceed  $12,000,000.  As used
herein, the term "Restricted Payments" shall mean,  collectively,  (i) Dividends
and (ii) any (A) payment or prepayment  of principal,  premium or penalty on any
subordinated  indebtedness  of  Borrower  or  any of  its  subsidiaries,  or any
defeasance,  redemption, purchase, repurchase or other acquisition or retirement
for value,  in whole or in part, of any  subordinated  indebtedness  (including,
without  limitation,  the  setting  aside  of  assets  of the  deposit  of funds
therefore),  other than the  conversion  thereof  into  capital  stock,  and (B)
prepayment of interest on any  subordinated  indebtedness.  As used herein,  the
term "Dividends" shall mean, as to Borrower or any of its subsidiaries,  (i) any
declaration or payment of any dividend  (other than a stock dividend) on, or the
making of any distribution,  loan, advance or investment to or in any holder of,
any shares of capital stock of, or other similar  interest in,  Borrower or such
subsidiary and (ii) any purchase,  redemption or other acquisition or retirement
for value of any shares of capital stock of, or similar interest in, Borrower or
such subsidiary.

     5.8 Affiliate Transactions.  Borrower will not transfer any property to its
stockholders or any affiliate of its stockholders,  except for value received in
the normal course of business as business  would be conducted  with an unrelated
or unaffiliated entity.

     5.9 Capital  Expenditures.  Borrower will not make, and will not permit any
of its  subsidiaries to make,  capital  expenditures in excess of Thirty Million
Dollars  ($30,000,000)  in the aggregate in any fiscal year; and shall only make
such  expenditures  as are  necessary for Borrower and its  subsidiaries  in the
conduct of its ordinary course of business.  Each capital  expenditure  shall be
needed by  Borrower or any of its  subsidiaries  in the  ordinary  course of its
business.  As used herein,  the term  "capital  expenditures"  shall include the
current expense  portion of all leases,  whether or not  capitalized,  and shall
also include the current  portion of any  indebtedness  used to finance  capital
expenditures.

     SECTION 6. EVENTS OF DEFAULT

     The  occurrence of any of the following  events  (collectively,  "Events of
Default") shall terminate any obligation on the part of Bank to make or continue
the Loan and automatically, unless otherwise provided under the Note, shall make
all sums of interest and  principal  and any other  amounts owing under the Loan
immediately  due and payable,  without notice of default,  presentment or demand
for payment,  protest or notice of nonpayment or dishonor,  or any other notices
or demands:

     6.1 Borrower shall default in the due and punctual payment of the principal
of or the interest on the Note or any of the other Loan Documents; or

     6.2 Any default shall occur under the Note; or

<PAGE>

                                                                   EXHIBIT 10.11

     6.3 Borrower  shall  default in the due  performance  or  observance of any
covenant or condition of the Loan Documents; or

     6.4 Any guaranty or subordination required hereunder is breached or becomes
ineffective,  or any Guarantor or  subordinated  creditor shall die,  disavow or
attempt to revoke or terminate such guaranty or subordination.

     SECTION 7. MISCELLANEOUS PROVISIONS

     7.1  Additional  Remedies.  The rights,  powers and remedies  given to Bank
hereunder  shall be cumulative and not  alternative  and shall be in addition to
all rights,  powers and  remedies  given to Bank by law against  Borrower or any
other  person,  including but not limited to Bank's rights of setoff or banker's
lien.

     7.2  Nonwaiver.  Any  forbearance or failure or delay by Bank in exercising
any right,  power or remedy  hereunder  shall not be deemed a waiver thereof and
any single or partial exercise of any right,  power or remedy shall not preclude
the further exercise thereof.  No consent or waiver shall be effective unless it
is in writing and signed by an officer of Bank.

     7.3 Inurement. The benefits of this Agreement shall inure to the successors
and assigns of Bank and the permitted  successors  and assigns of Borrower,  and
any assignment by Borrower without Bank's consent shall be null and void.

     7.4 Applicable Law. This Agreement and all other agreements and instruments
required by Bank in connection  therewith  shall be governed by and construed in
accordance with the laws of the State of California.

     7.5  Severability.  Should any one or more  provisions of this Agreement be
determined to be illegal or  unenforceable,  all other  provisions  nevertheless
shall be effective.  In the event of any conflict between the provisions of this
Agreement  and  the  provisions  of  the  Note  or any  reimbursement  agreement
evidencing  any  indebtedness  hereunder,  the  provisions  of the  Note or such
reimbursement agreement shall prevail.

     7.6  Integration  Clause.  Except for the Loan  Documents,  this  Agreement
constitutes the entire  agreement  between Bank and Borrower  regarding the Loan
and all prior  communications,  whether verbal or written,  between Borrower and
Bank shall be of no further effect or evidentiary value.

     7.7  Construction.  The  section  and  subsection  headings  herein are for
convenience  of  reference  only and  shall not limit or  otherwise  affect  the
meaning hereof.

     7.8 Amendments. This Agreement may be amended only in writing signed by all
parties hereto.

     7.9 Counterparts. Borrower and Bank may execute one or more counterparts to
this  Agreement,  each of which shall be deemed an original,  but when  together
shall be one and the same instrument.

     7.10 Confidentiality. Bank agrees to hold any confidential information that
it may receive from Borrower pursuant to this Agreement or the Loan Documents in
confidence, except

<PAGE>

                                                                   EXHIBIT 10.11

that Bank may disclose such confidential  information (a) to affiliates of Bank,
(b) to  legal  counsel  and  accountants  for  Borrower  or  Bank,  (c) to other
professional  advisors to  Borrower or Bank,  provided  that the  recipient  has
accepted such confidential  information  subject to a confidentiality  agreement
substantially  similar to this Section 7.10, (d) to regulatory  officials having
jurisdiction  over Bank, (e) as required by law or legal process,  provided that
Bank agrees to notify  Borrower of any such  disclosures  unless  prohibited  by
applicable  law, or in  connection  with any legal  proceeding to which Bank and
Borrower  are  adverse  parties,  and (f) to another  financial  institution  in
connection  with  a  disposition  or  proposed  disposition  to  that  financial
institution  of all or part of Bank's  interests  hereunder  or a  participation
interest in the Note, provided that the recipient has accepted such confidential
information subject to a confidentiality agreement substantially similar to this
Section 7.10. For purposes of the foregoing,  "confidential  information"  shall
mean any information  respecting Borrower or any of its subsidiaries  reasonably
considered by Borrower to be confidential, other than (i) information previously
filed with any governmental agency and available to the public, (ii) information
previously  published in any public medium from a source other than, directly or
indirectly,  Bank, and (iii) information previously disclosed by Borrower to any
person or entity not associated  with Borrower which does not owe a professional
duty of  confidentiality  to Borrower or which has not  executed an  appropriate
confidentiality  agreement with Borrower.  Nothing in this Section 7.10 shall be
construed  to create or give rise to any  fiduciary  duty on the part of Bank to
Borrower.

     SECTION 8. NOTICES

     8.1 Any notices or other  communications  provided for or allowed hereunder
shall be effective only when given by one of the following methods and addressed
to the  respective  party at its address given with the signatures at the end of
this  Agreement  and shall be considered  to have been validly  given:  (a) upon
delivery,  if delivered  personally;  (b) upon receipt,  if mailed,  first class
postage prepaid, with the United States Postal Service; (c) on the next business
day, if sent by overnight courier service of recognized  standing;  and (d) upon
telephoned confirmation of receipt, if telecopied.

     8.2 The  addresses  to which  notices  or  demands  are to be given  may be
changed from time to time by notice delivered as provided above.

<PAGE>

                                                                   EXHIBIT 10.11

     THIS  AGREEMENT  is  executed  on  behalf  of the  parties  by  their  duly
authorized officers as of the date first above written.

TEKELEC

By_______________________

Title:___________________

By_______________________

Title:___________________

Address:

Tekelec
26580 Aguora Road
Calabasas, California 91302
Attention: Mr. Paul J. Pucino
           Vice President &
           Chief Financial Officer

Telecopier No.: 818-880-0176
Telephone No.: 818-880-7921

UNION BANK OF CALIFORNIA, N.A.

By_______________________

Title:___________________

Address:

Union Bank of California, N.A.
445 South Figueroa Street,
10th Floor
Los Angeles, California 90071
Attention: John Kase
           Vice President &
           Senior Credit Executive
Telecopier No.: 213-236-7637
Telephone No.: 213-236-7329

<PAGE>

                                                                   EXHIBIT 10.11

                                 PROMISSORY NOTE

   UNION
  BANK OF                      PROMISSORY NOTE
CALIFORNIA                        BASE RATE

                                                                   BATIE/R/11198
--------------------------------------------------------------------------------
Borrower Name     TEKELEC
--------------------------------------------------------------------------------
Borrower Address              Office         Loan Number
                              30361          8903510826    0008-00-0-000
                            ----------------------------------------------------
26580 W. AGOURA ROAD          Maturity Date           Amount
CALABASAS, CA 91302           OCTOBER 31, 2002        $20,000,000.00
--------------------------------------------------------------------------------

Date OCTOBER 31, 2001                                             $20,000,000.00

FOR VALUE RECEIVED,  on OCTOBER 31, 2002 the undersigned  ("Debtor") promises to
pay to the order of UNION BANK OF CALIFORNIA, N.A. ("Bank"), as indicated below,
the principal sum of TWENTY MILLION AND NO/100 Dollars  ($20,000,000.00),  or so
much  thereof as is  disbursed,  together  with  interest on the balance of such
principal from time to time outstanding, at a per annum rate or rates and at the
times set forth below.

1.  INTEREST  PAYMENTS.  Debtor shall pay interest on the 30th day of each MONTH
commencing  NOVEMBER  30, 2001.  Should  interest not be paid when due, it shall
become a part of the principal and thereafter bear interest as herein  provided.
All  computations  of  interest  under this note shall be made on the basis of a
year of 360 days, for actual days elapsed.

      a. BASE INTEREST RATE. At Debtor's option,  amounts outstanding  hereunder
      in minimum amounts of at least  $500,000.00  shall bear interest at a rate
      based on an index selected by Debtor,  which is 1.500% per annum in excess
      of  Bank's  LIBOR  Rate  for  the  Interest  Period  selected  by  Debtor,
      acceptable to Bank.

      No Base Interest Rate may be changed,  altered or otherwise modified until
      the expiration of the Interest Period selected by Debtor.  The exercise of
      interest  rate options by Debtor  shall be as recorded in Bank's  records,
      which records shall be prima facie  evidence of the amount  borrowed under
      either  interest  option and the interest rate;  provided,  however,  that
      failure  of Bank to make  any  such  notation  in its  records  shall  not
      discharge  Debtor from its  obligations to repay in full with interest all
      amounts borrowed.  In no event shall any Interest Period extend beyond the
      maturity date of this note.

      To exercise  this  option,  Debtor may,  from time to time with respect to
      principal  outstanding on which a Base Interest Rate is not accruing,  and
      on the  expiration  of any  Interest  Period  with  respect  to  principal
      outstanding  on which a Base  Interest Rate has been  accruing,  select an
      index  offered  by Bank for a Base  Interest  Rates  Loan and an  Interest
      Period by telephoning an authorized lending officer of Bank located at the
      banking office identified below prior to 10:00 a.m.,  Pacific time, on any
      Business Day and advising that officer of the selected index, the Interest
      Period and the Origination  Date selected (which  Origination  Date, for a
      Base Interest Rate Loan based on the LIBOR Rate,  shall follow the date of
      such selection by no more than two (2) Business Days).

      Bank will mail a written  confirmation  of the terms of the  selection  to
      Debtor  promptly  after  the  selection  is  made.  Failure  to send  such
      confirmation  shall not affect  Bank's  rights to collect  interest at the
      rate  selected.  If, on the date of the  selection,  the index selected is
      unavailable for any reason, the selection shall be void. Bank reserves the
      right to fund the principal from any source of funds  notwithstanding  any
      Base Interest Rate selected by Debtor.

      b. VARIABLE  INTEREST RATE. All principal  outstanding  hereunder which is
      not bearing interest at a Base Interest Rate shall bear interest at a rate
      per annum equal to the Reference  Rate,  which rate shall vary as and when
      the Reference Rate changes.

      If any interest rate defined in this note ceases to be available from Bank
      for any reason, then said interest rate shall be replaced by the rate then
      offered by Bank,  which,  in the sole  discretion  of Bank,  most  closely
      approximates the unavailable rate.

      At any time prior to the maturity of this note,  subject to the provisions
      of paragraph 4, below, of this note, Debtor may borrow, repay and reborrow
      hereon so long as the total  outstanding  at any one time does not  exceed
      the principal amount of this note.  Debtor shall pay all amounts due under
      this note in lawful  money of the  United  States at Bank's  SAN  FERNANDO
      VALLEY  COMMERCIAL  BANKING  Office,  or  such  other  office  as  may  be
      designated by Bank, from time to time.

2. LATE PAYMENTS. If any payment required by the terms of this note shall remain
unpaid ten days after same is due, at the option of Bank, Debtor shall pay a fee
of $100 to Bank.

3. INTEREST RATE FOLLOWING  DEFAULT.  In the event of default,  at the option of
Bank,  and, to the extent  permitted  by law,  interest  shall be payable on the
outstanding  principal  under  this note at a per annum  rate  equal to FIVE AND
NO/100  percent  (5,000%) in excess of the interest rate  specified in paragraph
1.b, above,  calculated from the date of default until all amounts payable under
this note are paid in full.

4. PREPAYMENT.

a. Amounts  outstanding  under this note bearing interest at a rate based on the
Reference Rate may be prepaid in whole or in part at any time,  without  penalty
or  premium.  Debtor  may repay  amounts  outstanding  under  this note  bearing
interest at a Base Interest  Rate in whole or in part provided  Debtor has given
Bank not less than five (5)  Business  Days  prior  written  notice of  Debtor's
intention to make such  prepayment  and pays to Bank the prepayment fee due as a
result.  The  prepayment  fee shall also be paid, if Bank, for any other reason,
including acceleration or foreclosure,  receives all or any portion of principal
bearing  interest at a Base Interest  Rate prior to its scheduled  payment date.
The  prepayment fee shall be an amount equal to the present value of the product
of: (i) the  difference  (but not less than zero)  between (a) the Base Interest
Rate  applicable to the  principal  amount which is being  prepaid,  and (b) the
return  which Bank  could  obtain if it used the  amount of such  prepayment  of
principal to purchase at bid price  regularly  quoted  securities  issued by the
United States having a maturity date most closely coinciding with

<PAGE>

                                                                   EXHIBIT 10.11

the relevant Base Rate Maturity Date and such securities were held by Bank until
the relevant  Base Rate  Maturity  Date  ("Yield  Rate");  (ii) a fraction,  the
numerator  of which is the  number  of days in the  period  between  the date of
prepayment and the relevant Base Rate Maturity Date and the denominator of which
is 360; and (iii) the amount of the  principal  so prepaid  (except in the event
that principal  payments are required and have been made as scheduled  under the
terms of the Base Interest Rate Loan being prepaid,  then an amount equal to the
lesser of (A) the amount prepaid or (B) 50% of the sum of (1) the amount prepaid
and (2) the amount of principal  scheduled  under the terms of the Base Interest
Rate Loan being  prepaid to be  outstanding  at the relevant  Base Rate Maturity
Date).  Present  value under this note is determined  by  discounting  the above
product to present value using the Yield Rate as the annual discount factor.

b. In no event shall Bank be  obligated to make any payment or refund to Debtor,
nor shall Debtor be entitled to any setoff or other claim against  Bank,  should
the return  which Bank could  obtain under this  prepayment  formula  exceed the
interest  that Bank would have  received  if no  prepayment  had  occurred.  All
prepayments shall include payment of accrued interest on the principal amount so
prepaid  and shall be  applied  to payment of  interest  before  application  to
principal.  A  determination  by Bank as to the prepayment  fee amount,  if any,
shall be conclusive.

c. Bank shall  provide  Debtor a statement  of the amount  payable on account of
prepayment.  Debtor  acknowledges that (i) Bank establishes a Base Interest Rate
upon the  understanding  that it apply to the Base  Interest  Rate  Loan for the
entire Interest Period,  and (ii) Bank would not lend to Debtor without Debtor's
express agreement to pay Bank the prepayment fee described above.

Debtor initial here:  /s/
                      ------------------------------

5. DEFAULT AND ACCELERATION OF TIME FOR PAYMENT.  Default shall include, but not
be  limited  to,  any of the  following:  (a) the  failure of Debtor to make any
payment required under this note when due; (b) any breach,  misrepresentation or
other default by Debtor,  any guarantor,  co-maker,  endorser,  or any person or
entity  other  than  Debtor  providing   security  for  this  note  (hereinafter
individually and  collectively  referred to as the "Obligor") under any security
agreement,  guaranty or other  agreement  between Bank and any Obligor;  (c) the
insolvency  of any Obligor or the failure of any Obligor  generally  to pay such
Obligor's debts as such debts become due; (d) the commencement as to any Obligor
of  any  voluntary  or  involuntary   proceeding  under  any  laws  relating  to
bankruptcy, insolvency,  reorganization,  arrangement, debt adjustment or debtor
relief;  (e) the  assignment  by any Obligor  for the benefit of such  Obligor's
creditors;  (f) the  appointment,  or  commencement  of any  proceeding  for the
appointment  of a receiver,  trustee,  custodian or similar  official for all or
substantially  all  of any  Obligor's  property;  (g)  the  commencement  of any
proceeding  for  the  dissolution  or  liquidation  of  any  Obligor;   (h)  the
termination  of  existence or death of any Obligor;  (i) the  revocation  of any
guaranty or subordination  agreement given in connection with this note; (j) the
failure of any Obligor to comply with any order, judgement,  injunction, decree,
writ or  demand  of any  court or other  public  authority;  (k) the  filing  or
recording against any Obligor,  or the property of any Obligor, of any notice of
levy,  notice to withhold,  or other legal process for taxes other than property
taxes;  (l) the  default  by any  Obligor  personally  liable for  amounts  owed
hereunder on any obligation  concerning the borrowing of money; (m) the issuance
against any Obligor,  or the property of any Obligor, of any writ of attachment,
execution,  or other  judicial lien; or (n) the  deterioration  of the financial
condition of any Obligor  which results in Bank deeming  itself,  in good faith,
insecure. Upon the occurrence of any such default, Bank, in its discretion,  may
cease to advance funds hereunder and may declare all obligations under this note
immediately due and payable; however, upon the occurrence of an event of default
under d, e, f, or g, all  principal  and  interest  shall  automatically  become
immediately due and payable.

6. ADDITIONAL AGREEMENTS OF DEBTOR. If any amounts owing under this note are not
paid  when  due,  Debtor  promises  to pay all  costs  and  expenses,  including
reasonable attorneys' fees, incurred by Bank in the collection or enforcement of
this note. Debtor and any endorsers of this note, for the maximum period of time
and the full extent permitted by law, (a) waive diligence,  presentment, demand,
notice of nonpayment,  protest, notice of protest, and notice of every kind; (b)
waive the right to assert the defense of any statute of  limitations to any debt
or obligation hereunder;  and (c) consent to renewals and extensions of time for
the payment of any  amounts due under this note.  If this note is signed by more
than one party,  the term  "Debtor"  includes  each of the  undersigned  and any
successors  in  interest  thereof;  all of whose  liability  shall be joint  and
several.  Any married person who signs this note agrees that recourse may be had
against the separate property of that person for any obligations hereunder.  The
receipt of any check or other item of payment by Bank, at its option,  shall not
be  considered a payment on account until such check or other item of payment is
honored when presented for payment at the drawee bank. Bank may delay the credit
of such payment based upon Bank's schedule of funds  availability,  and interest
under this note shall accrue until the funds are deemed collected. In any action
brought  under or arising out of this note,  Debtor and any  Obligor,  including
their  successors  and  assigns,  hereby  consent  to  the  jurisdiction  of any
competent  court within the State of California,  as provided in any alternative
dispute  resolution  agreement  executed between Debtor and Bank, and consent to
service of process by any means  authorized by said state's law. The term "Bank"
includes,  without  limitation,  any  holder of this  note.  This note  shall be
construed  in  accordance  with  and  governed  by  the  laws  of the  State  of
California.  This note hereby  incorporates any alternative  dispute  resolution
agreement  previously,  concurrently  or hereafter  executed  between Debtor and
Bank.

7.  DEFINITIONS.  As used herein,  the  following  terms shall have the meanings
respectively  set forth  below:  "Base  Interest  Rate" means a rate of interest
based on the LIBOR Rate.  "Base  Interest Rate Loan" means  amounts  outstanding
under this note that bear interest at a Base Interest Rate.  "Base Rate Maturity
Date"  means the last day of the  Interest  Period  with  respect  to  principal
outstanding under a Base Interest Rate Loan. "Business Day" means a day on which
Bank is open for business for the funding of corporate loans,  and, with respect
to the rate of  interest  based on the LIBOR  Rate,  on which  dealings  in U.S.
dollar  deposits  outside  of the  United  States  may be  carried  on by  Bank.
"Interest  Period" means with respect to funds bearing  interest at a rate based
on the LIBOR  Rate,  any  calendar  period of one,  three,  six,  nine or twelve
months. In determining an Interest Period, a month means a period that starts on
one  Business  Day in a month and ends on and  includes  the day  preceding  the
numerically corresponding day in the next month. For any month in which there is
no such numerically  corresponding day, then as to that month, such day shall be
deemed to be the last  calendar  day of such month.  Any  Interest  Period which
would  otherwise  end on a  non-Business  Day shall  end on the next  succeeding
Business  Day  unless  that is the first  day of a month,  in which  event  such
Interest Period shall end on the next preceding Business Day. "LIBOR Rate" means
a per annum rate of interest (rounded upward, if necessary, to the nearest 1/100
of 1%) at which dollar  deposits,  in immediately  available funds and in lawful
money of the  United  States  would be  offered  to Bank,  outside of the United
States,  for a term  coinciding  with the Interest Period selected by Debtor and
for an amount equal to the amount of principal covered by Debtor's interest rate
selection,   plus  Bank's  costs,   including  the  cost,  if  any,  of  reserve
requirements.  "Origination  Date" means the first day of the  Interest  Period.
"Reference  Rate"  means  the rate  announced  by Bank  from time to time at its
corporate  headquarters  as its Reference  Rate.  The Reference Rate is an index
rate  determined  by Bank  from  time to time  as a  means  of  pricing  certain
extensions  of credit  and is  neither  directly  tied to any  external  rate of
interest or index nor necessarily the lowest rate of interest charged by Bank at
any given time.

TEKELEC

By: /s/                               VP, Corporate Controller
    __________________________________________________________________
    Title

By: /s/                               VP, Chief Financial Officer
    __________________________________________________________________
    TitleEXHIBIT 10.15

November 13, 2001

PERSONAL AND CONFIDENTIAL                                    Via Federal Express

Lori A. Craven
1111 Kenilworth Circle
Naperville, IL  60540

Dear Lori:

On behalf of Tekelec, I am pleased to offer you employment as Vice President and
General Manager, Network Systems Division, on the terms and conditions set forth
in this letter. As Vice President and General Manager, Network Systems Division,
you will  report  directly  to  Tekelec's  Executive  Vice  President  and Chief
Operating Officer, will be principally responsible for Tekelec's Network Systems
Division  and  will  have  such  other  duties  and  responsibilities  as may be
delegated to you from time to time by the  Executive  Vice  President  and Chief
Operating  Officer  and/or the Chief  Executive  Officer.  You may  choose  your
employment  start  date so long as it is on or  before  January  2,  2002.  Your
compensation and benefits will be as follows:

1.   Your  starting  annual base salary will be $225,000  (i.e.,  $8,653.85  per
     bi-weekly period).

2.   You will be eligible to  participate  in Tekelec's 2002 Officer Bonus Plan,
     under which you will be eligible to receive,  in accordance  with the terms
     of such  Plan as  approved  by the  Company's  Board  of  Directors  (which
     approval is expected  prior to March  2002),  up to 56% of your annual base
     salary  earned  during  2002 as a cash  bonus  based on  certain  financial
     milestones  in 2002 and an annual  bonus  equal to 14% of your  annual base
     salary  earned  during 2002 if you achieve  certain  individual  objectives
     during 2002.  For 2002,  you will be  guaranteed a minimum bonus of $39,375
     which,  if due, will be paid during the first quarter of 2003. This minimum
     bonus represents 25% of the maximum  aggregate bonus for which you would be
     eligible under the 2002 Officer Bonus Plan. The terms of your participation
     in any  officer  bonus  plans  after 2002 will be subject to change and the
     approval of the Board of Directors of Tekelec.

3.   You will be entitled to take four weeks personal time annually.

4.   You will receive applicable  benefits,  including health,  dental,  vision,
     long-term  disability  and life  insurance,  as are  generally  provided to
     Tekelec's executive officers.

5.   You will be offered the  opportunity to  participate in Tekelec's  Employee
     Stock  Purchase  Plan  and  401(k)  Plan  upon  your  satisfaction  of  the
     eligibility requirements for such plans.

6.   You will be covered by Tekelec's Officer Severance Plan (a copy of which is
     enclosed).

7.   The  Compensation  Committee  of Tekelec  will  grant to you stock  options
     (incentive  stock options to the maximum extent  permitted  under law, with
     the balance being  nonstatutory  stock options) under  Tekelec's 1994 Stock
     Option Plan (the "Plan") to purchase 200,000

<PAGE>

                                                                   EXHIBIT 10.15

     shares of Tekelec  Common Stock  ("Options"),  effective as of the later of
     your start date or the date of the Compensation Committee's action granting
     such options (the "grant date"). The exercise price of your Options will be
     equal to the closing price of Tekelec's  Common Stock on the grant date (as
     reported in The Wall Street Journal on the first business day following the
     grant date).  Your Options will vest to the extent of 50,000  shares on the
     one-year  anniversary of your start date. The remaining 150,000 shares will
     vest and become exercisable cumulatively in 12 equal quarterly installments
     of 12,500 shares each, with the first  installment  vesting on the last day
     of the first full calendar quarter  following your one-year  anniversary of
     employment with the Company) and one additional  installment vesting on the
     last day of each  calendar  quarter  thereafter  as long as you  remain  an
     employee of Tekelec.  Your Options will  expire,  to the extent  previously
     unexercised, upon the earlier of ten years from the date of grant or a date
     not less than  three  months  after you cease to be a Tekelec  employee  as
     determined  in accordance  with the terms of the Plan.  The Options will in
     all  respects  be subject to the terms and  provisions  of the Plan and the
     stock option agreement  evidencing the grant of the Options. In addition to
     the foregoing grant, it is anticipated that the Compensation Committee will
     periodically,  typically  annually,  consider  whether  additional  options
     should be granted to you while you remain an officer of the Company.

8.   Tekelec will pay you up to a maximum of $100,000 to reimburse  you for your
     accountable  costs incurred in relocating to North Carolina,  including the
     anticipated  commissions and fees for the sale of your current home, losses
     (if any) incurred on the sale of your current  home,  the closing costs you
     incur in  connection  with your  purchase of a new home in North  Carolina,
     your  actual  out-of-pocket  travel,  moving,  rental  and  other  expenses
     relating  to your  relocation,  the  costs of  temporary  housing  in North
     Carolina pending your relocation and the reasonable  transportation expense
     you incur  traveling  to such  location  and the  associated  income  taxes
     payable by you with  respect  to your  receipt  of such  reimbursement.  In
     addition,  Tekelec will  reimburse you for the  reasonable  expenses of one
     house-hunting trip to North Carolina.

You  are  aware  that  Tekelec   prohibits   employees  from  unlawfully   using
confidential or proprietary information belonging to any other person or entity.
By signing the enclosed copy of this letter, you agree not to disclose or use or
induce Tekelec or any of its employees to use any trade secrets or  confidential
or proprietary information belonging to any of your former employers.

As a condition of commencing your employment with Tekelec,  you will be required
to sign Tekelec's standard  "Confidentiality  and  Non-Disclosure  Agreement and
Assignment  of Rights"  (a copy of which is  enclosed).  As with  every  Tekelec
employee, you reserve the right to terminate your employment at any time for any
reason,  and we similarly  reserve the right to terminate your employment at any
time,  with or without cause. We hope and expect,  however,  that this will be a
long and mutually beneficial relationship.

This letter  agreement  contains our entire  understanding  with respect to your
employment with Tekelec.  The provisions of this letter may be amended only by a
writing signed by you and Tekelec.  If you have any questions  about the meaning
of any of the terms or provisions  included  herein,  please let me know at your
earliest convenience. This letter agreement shall be construed under the laws of
California.

<PAGE>

                                                                   EXHIBIT 10.15

Lori,  we  believe  that  Tekelec  can  provide  you  with   opportunities   for
professional  growth and financial  return.  We look forward to working with you
and to a mutually fulfilling and rewarding relationship.

If this letter  agreement is  acceptable to you,  then please  acknowledge  your
acceptance  by signing and dating the  enclosed  copy of this  letter  agreement
where indicated below and then faxing (fax number:  818.880.0176)  and returning
such signed copy to me for receipt no later than November 15, 2001.

Sincerely,

Fred Lax
Executive Vice President and Chief Operating Officer

Acknowledged and Accepted:

/S/                     Date: November 15, 2001
---------------------
Lori A. Craven

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