<PAGE>   1
                                                                 EXHIBIT 10.1




                      AUTHORIZED SALES SUBAGENT AGREEMENT


       AGREEMENT made this 1 day of April 1997 by and between L.D. 
COMMUNICATIONS, INC. ("LDCI"), 6575 West Loop South, Suite 420, Bellaire, TX 
77401 a Texas Corporation and XETA Corporation ("Subagent"), An Oklahoma 
Corporation, with principal offices located at 4500 S Garnett, Suite 1000, 
Tulsa OK 74146.

       WHEREAS, LDCI wishes to expand all commercial entities' access to MCI
Commercial Dial "1" Long Distance Service, MCI Prism Plus, MCI Prism I, MCI
Preferred, MCI Vision, MCI 800, MCI Card, MCI Corporate Account Service, MCI
Corporate Account Service Plus, MCI Hospitality Services, Dedicated Leased Line
Services and MCI Forum (the "MCI Services"), as described in MCI Tariff FCC No
1, any state tariff, and amendments thereto or successor tariffs (together, the
"Tariff"); and

       WHEREAS, Subagent desires to market the MCI Services set forth herein as
an independent Authorized Sales Subagent of LDCI;

       NOW, THEREFORE,  the parties agree as follows:

1.     Grant of Subagency.  Subject to the terms of this agreement, Subagent is
       hereby appointed an independent subagent authorized to solicit, on
       behalf of MCI, commercial customers (as distinguished from residential
       customers) for MCI Services.

2.     Sales Subagency.

       a)     Subagent hereby accepts the appointment by LDCI as its authorized
              representative to solicit orders from commercial customer for MCI
              Services subject to the terms and conditions of this Agreement.

       b)     LDCI shall pay subagent a commission on monthly usage revenues
              from orders for Services solicited by Agency and accepted by MCI,
              based on the commission table below.  Commission percentage is
              based on total monthly revenues.

<TABLE>
                     <S>                                <C>
                     $        0 -  XX9,999               XX %
                     $  X00,000 -  X99,999               XX %
                     $  X00,000 -  X99,999               XX %
                     $  X00,000 -  X99,999               XX %
                     $  X00,000 and above                XX %
</TABLE>

       The monthly usage revenues eligible for commission hereunder include
       monthly recurring usage revenue from services sold by Subagent but do
       not include:  1) any MCI charges for goods or services that are not
       tariffed;  2) pass through access/egress (or related) charges imposed by
       third parties;  3) any non-recurring charge imposed in MCI Tariff FCC
       No.1;  4) MCI Directory Assistance Services;  5) any taxes or surcharges
       applicable to services; and  6) any promotional or other credits granted
       by MCI.

       The effective rate of commissions hereunder will be derived by applying
       the applicable commission rate set forth above to eligible charges
       incurred under MCI Tariff FCC No. 1 during a monthly billing period.



                                       1


CONFIDENTIAL AGENT INFORMATION                                         LDCI 3/97

AGENT INITIAL____________                               LDCI INITIAL____________
<PAGE>   2
       c)     Unless otherwise agreed in writing by LDCI, commission shall not
              be payable for monthly usage derived from any person or entity
              that was an MCI customer at the time of order solicitation or
              within thirty (30) days prior thereto.  Commission shall not be
              payable on monthly usage derived from any person or entity that
              is an MCI National account.  Commission shall not be payable on
              any usage derived from any person or entity controlled by
              Subagent.

       d)     Subagent shall not solicit orders by means of telemarketing
              without prior written consent of LDCI. If Subagent solicits by
              means of telemarketing, Subagent shall coordinate with LDCI to
              ensure that no PIC change order resulting from telemarketing is
              submitted without confirmation by one of the means required by
              FCC regulations.  MCI may take steps to confirm compliance with
              this provision including without limitation contacting MCI
              customers solicited by Subagent.

       e)     Subagent may not delegate all or any portion of the Subagency
              appointment under this Agreement to any third party without prior
              express written consent of LDCI and under a written agreement
              satisfactory to LDCI.  Breach of this provision shall be deemed
              an irregular marketing activity.  LDCI shall not be liable to pay
              commissions under this Agreement or otherwise for revenue
              generated by any unauthorized subagent.

3.     Relationship Of Parties.

       a)     Subagent will have no authority to bind LDCI or MCI by contract
              or otherwise or to make representations as to the policies or
              procedures of LDCI/MCI other than as specifically authorized by
              the Agreement.  LDCI/MCI and Subagent acknowledge and agree that
              their Subagency relationship arising from this Agreement does not
              constitute or create a general agency, joint venture,
              partnership, employee relationship or franchise between them and
              that Subagent is an independent contractor with respect to the
              services provided by it under this Agreement.

       b)     Subagent will identify itself as an Authorized Sales Agent of MCI
              only with respect to the MCI Services and will otherwise identify
              itself as an independent business.  Unless specifically
              authorized in writing, neither LDCI/MCI nor Subagent will make
              any express or implied agreement, guarantees or representations,
              or incur any debt, in the name of or on behalf of the other.

       c)     Subagent's employees will not be deemed to be LDCI/MCI employees
              or joint employees and for their supervision, daily direction and
              control.  LDCI/MCI will not be responsible for worker's
              compensation, disability benefits, unemployment insurance,
              withholding taxes, social security and other taxed and benefits
              for Subagent's employees.

4.     Training And Certification.

       a)     MCI shall provide product sales training for each of the MCI
              services as provided for in this agreement.  Subagent and
              Subagent employees may not solicit orders for any MCI Services
              until trained in product sales for that product by MCI.

5.     Sales Aids.

       a)     Subagent shall us LDCI/MCI-approved marketing materials and order
              forms only.





                                       2


CONFIDENTIAL AGENT INFORMATION                                         LDCI 3/97

AGENT INITIAL____________                               LDCI INITIAL____________
<PAGE>   3
       b)     SUBAGENT SHALL MAKE NO REPRESENTATION OR WARRANTIES RELATING TO
              THE SERVICES EXCEPT AS SET FORTH IN SALES LITERATURE APPROVED IN
              WRITING BY LDCI/MCI OR AS SET FORTH IN THE FORM OR FORMS OF
              ORDERS PROVIDED BY SUBAGENT BY LDCI/MCI, OR AS OTHERWISE
              EXPRESSLY PERMITTED BY LDCI/MCI.

6.     Reporting; Payment.

       a)     LDCI will provide Subagent with monthly commission reporting,
              which will include the usage of each customer solicited by
              Subagent and for which commission is due hereunder.

       b)     LDCI will pay commissions monthly.  LDCI will use reasonable
              efforts to calculate and pay commissions within ten (10) days
              following payment to LDCI by MCI, which is approximately sixty
              (60) days after the close of an applicable billing month.

7.     Order Acceptance.

       Subagent expressly acknowledges that its appointment hereunder is as a
       sales representative for MCI Services offered through LDCI, that any
       solicitation by Subagent of orders from customers for the MCI services
       will be subject to MCI's acceptance, in its sole discretion, of such
       orders and the availability, from time to time, of the MCI Services, and
       that LDCI will have no responsibility or liability whatsoever to
       Subagent with respect to continued availability or operation of the MCI
       Services or MCI's acceptance or, or failure to accept, orders therefore
       from customers solicited by Subagent.

8.     Standards Of Conduct.

       In performing duties under this Agreement, Subagent will observe the
       highest standard of integrity and fair dealing with members of the
       public.  Subagent will do nothing which would tend to discredit,
       dishonor, reflect adversely upon or in any manner injure the reputation
       of LDCI or MCI.

9.     Tradenames And Trademarks.

       a)     During the term of this Agreement, unless otherwise instructed by
              MCI, Subagent may refer to itself as an MCI Authorized Sales
              Agent, but solely in connection with the marketing of MCI
              Services to commercial customers hereunder.  Subagent may use
              only such other MCI trademarks, tradenames, and services marks
              ("Marks") as may be authorized by MCI in writing, subject to any
              and all limitations contained in the grant of the right of such
              use.

       b)     Upon termination of this Agreement, any permission or right to
              Marks granted hereunder will cease to exist and Subagent will
              immediately cease any use of such marks and immediately cease
              referring to itself as an MCI Authorized Sales Agent

10.    Non-Competition/Confidentiality.

       a)     During the term of this agreement and for as long as LDCI is
              paying commission under this Agreement but in no event for fewer
              than ninety (90) days after termination of the Agreement subagent
              will not promote, sell or provide leads for the services to





                                       3


CONFIDENTIAL AGENT INFORMATION                                         LDCI 3/97

AGENT INITIAL____________                               LDCI INITIAL____________
<PAGE>   4
              commercial customer, of any other person or entity that offers
              services identical or similar to any one or more of the MCI
              services.

       b)     Any confidential specifications, drawing, sketches, data or
              technical material ("Information"), furnished or disclosed by
              LDCI/MCI to Subagent hereunder, will be deemed the exclusive
              property of LDCI/MCI. In addition, any customer names or lists
              identifying MCI customer as such and related information or data
              ("Customer Information") are the exclusive property of LDCI/MCI,
              and are to be used by Subagent solely in the performance of its
              obligations and duties hereunder and are to be returned to
              LDCI/MCI upon termination of this Agreement.

       c)     During the term of this Agreement and for a period of three (3)
              years after termination of this Agreement, Subagent agrees not to
              reveal, divulge, make known, sell, exchange, lease or in any
              other way transfer any Information or Customer Information to any
              third party or to utilize such Information or Customer
              Information in direct or indirect competition with MCI or any of
              its other Agents.  Subagent agrees that monetary damages for
              breach of its obligations under this section may not be adequate
              and that LDCI/MCI will be entitled to injunctive relief with
              respect thereto.  Notwithstanding the foregoing, it is understood
              and agreed that nothing herein shall prohibit the Subagent from
              selling either during or after the term of this Agreement,
              telecommunications systems (e.g., call accounting, voice mail,
              answer detection, PBX systems and related products) to hotels and
              other customers, including the MCI Services customers.  Moreover,
              upon termination of this agreement nothing herein shall prohibit
              Subagent from selling services offered by any other carrier that
              are similar or identical to the MCI services, to any MCI customer
              upon the expiration of such customer's contract for the MCI
              services.

       d)     LDCI hereby agrees to keep confidential all information
              concerning Subagent's activities under this Agreement and the
              amount of commissions paid to the Subagent hereunder or to the
              Subagent's customers, and will not disclose any such information
              to any third party (except MCI as may be necessary to enable MCI
              and/or LDCI to perform under this Agreement) or any other
              subagent of LDCI, except as may otherwise be required by law.

11.    Term And Termination.

       a)     The term of this Agreement is (3) three years and will thereafter
              be renewed automatically for an additional term of one (1) year
              unless either party notifies the other in writing of its desire
              to terminate the Agreement at least ninety (90) days prior to the
              expiration of the initial term.  This Agreement may be
              terminated: (a) immediately upon written notice from LDCI that
              LDCI's contract with MCI has been terminated; (b) for breach by
              Subagent of any provision of this Agreement provided that written
              notice of such breach has been given to Subagent and such breach
              has not been cured within thirty (30) days after delivery of such
              notice; (c) immediately upon notice by LDCI/MCI in the event
              LDCI/MCI discovers any irregular marketing activity by Subagent
              or irregular customer activity by customers solicited by
              Subagent.

       b)     After normal expiration of the term LDCI shall (a) continue to
              pay commission for a period of six (6) months at the commission
              rate applicable under Section 2.b. hereof (direct sales
              commission) for the last full month prior to expiration on
              monthly usage revenues calculated in accordance with Section 2.b.
              If LDCI terminated this Agreement pursuant to Section 11.a.(a)
              hereof, LDCI's commission payment obligations shall survive
              termination for a number of monthly equal to the number of
              completed calendar




                                       4


CONFIDENTIAL AGENT INFORMATION                                         LDCI 3/97

AGENT INITIAL____________                               LDCI INITIAL____________
<PAGE>   5
              months of the term of this Agreement prior to termination not to
              exceed six (6) months.  Upon termination for any other reason,
              LDCI's commission payment obligations shall cease.

12.    Limitation Of Liability.

       a)     Subagent agrees to hold LDCI free and harmless from any loss,
              damage, or cost, including legal expenses and counsel fees, that
              LDCI becomes liable for by reason of an act of Subagent in
              marketing in the Services, including but not limited to
              misrepresenting to customers the Services or the terms under
              which the  Services are made available by LDCI.  LDCI agrees to
              hold Subagent free and harmless from any loss, damage, or cost,
              including legal expenses and counsel fees, that Subagent becomes
              liable for to third persons by reason of any negligent or
              wrongful act of LDCI in the performance of this Agreement.

       b)     LDCI will have no liability to Subagent for commissions that
              might have been earned hereunder but for the inability or failure
              of MCI to provide Services to any person solicited by Subagent or
              in the event of discontinuation or modification of the Services.

       c)     Subagent acknowledges and agrees that LDCI directly or through
              other sales agents may offer MCI Services and that Subagent will
              be entitled to no compensation for sales make through such other
              channels.  In the event LDCI received conflicting orders for
              services from different subagents or MCI employees, LDCI/MCI may
              in its sole discretion determine who will receive credit for such
              orders.   In the event of such conflicts relating to orders for
              MCI Services, LDCI/MCI may in its discretion compensate Subagent
              as if the order were for a service subject to commission.

       d)     NEITHER PARTY WILL BE LIABLE TO THE OTHER FOR SPECIAL INDIRECT,
              CONSEQUENTIAL DAMAGES, WHETHER OR NOT FORESEEABLE, OR PUNITIVE
              DAMAGES.

       e)     In the event LDCI is required to enforce or preserve its rights
              hereunder, Subagent will pay all of LDCI's reasonable attorney's
              fees and costs, including allocable costs of in-house counsel,
              incurred in connection with any such successful action.

13.    Notices.

       Notices to be given pursuant to this Agreement will be in writing and
       will be deemed to have been duly and properly given on the earlier of
       (a) the date such notice has been received or (b) five (5) days after
       deposit of such notice in the United States Mail, postage prepaid, to be
       delivered by certified mail, return receipt requested addressed to the
       Subagent at the address given above or at such address as it may
       designate in writing from time to time and addressed to LDCI at:


                            Mr. Richard Akers, President & CEO
                            L.D Communications, Inc.
                            6575 West Loop South, Suite 420
                            Bellaire,  TX  77401


       or at such address it may designate in writing from time to time.





                                       5


CONFIDENTIAL AGENT INFORMATION                                         LDCI 3/97

AGENT INITIAL____________                               LDCI INITIAL____________
<PAGE>   6
14.    Compliance With Law.

       a)     Subagent will, at its own expense, operate in full compliance
              with all laws, rules and regulations applicable to, and maintain
              in force all licenses and permits required for, its performance
              under this Agreement.

       b)     Subagent will notify LDCI in writing immediately of the
              commencement or threatened commencement or any action, suite or
              proceeding, and if the issuance or threatened issuance of any
              order, writ, injunction, award of decree of any court, agency or
              other governmental instrumentality, involving Subagent's
              activities under this Agreement or which may affect Subagent's
              ability to perform its obligations hereunder.

15.    Non-Waiver.

       No failure by either party to take action on account of any default by
       the other will constitute a waiver of any such default or of the
       performance required of the other.

16.    Impossibility Of Performance.

       Neither LDCI/MCI nor Subagent will be liable for loss or damage or
       deemed to be in breach of this Agreement if its failure to perform its
       obligations results from (a) compliance with any law, ruling, order,
       regulation, requirement of federal, state or municipal government or
       department or agency thereof or court of competent jurisdiction; (b)
       acts of God; (c) acts of omissions of the other party; (d) fires,
       strikes, war, insurrection or riot; (e) or any other cause beyond its
       reasonable control.  Any delay resulting therefrom will extend
       performance accordingly or excuse performance, in whole or in part, as
       may be reasonable.

17.    Binding Effect.

       This Agreement will be binding upon and inure to the benefit of the
       parties their successors and assigns; provided, however, that Subagent
       may not assign or otherwise transfer this Agreement or any of its
       interest herein without the prior and express written consent thereto by
       LDCI.  Neither the whole nor any part of the interest of Subagent in
       this appointment will be transferred or assigned by operation of law.

18.    Severability.

       No provision of this Agreement which may be deemed unenforceable will in
       any way invalidate any other provision of this Agreement, all of which
       will remain in full force and effect.

19.    Controlling Law And Entire Agreement.

       This Agreement, with Attachments, will be governed by the domestic laws
       of the State of  Texas; constitutes the entire Agreement between
       Subagent and LDCI with respect to the subject matter hereof; and
       supersedes all prior Agreements and representations, written or oral,
       concerning the subject matter herein.  This Agreement cannot be changed
       or modified except by written amendment signed by Subagent and LDCI.





                                       6


CONFIDENTIAL AGENT INFORMATION                                         LDCI 3/97

AGENT INITIAL____________                               LDCI INITIAL____________
<PAGE>   7
20.    Heading.

       This section numbers and captions appearing in this Agreement are
       insured only as a matter of convenience and are in no way intended to
       define, limit, construe or describe the scope or intent of such sections
       of this Agreement, or in any way affect this Agreement.

       IN WITNESS THEREOF, the parties have executed this Agreement this 1st
       day of  April,  1997.



              XETA Corporation                    L.D. Communications, Inc.
       ----------------------------                                        
                 (Subagent)

              /s/ Jack R. Ingram                         /s/ Greg Fallin      
       ----------------------------               ----------------------------
           (Authorized Signature)                          Greg Fallin

              President                                  Vice President - Sales
       ----------------------------               -----------------------------
                (Title)                                     (Title)

              4/1/97                                     4/1/97               
       ----------------------------               ----------------------------
                (Date)                                      (Date)





                                       7



CONFIDENTIAL AGENT INFORMATION                                         LDCI 3/97

AGENT INITIAL____________                               LDCI INITIAL____________