<PAGE>

                                                                    EXHIBIT 10.2

                                AMENDMENT NO. 1
                                      TO
                             EMPLOYMENT AGREEMENT
                             --------------------



     This Amendment No. 1 to Employment Agreement (the "Amendment") is made and
                                                        ---------
entered into effective as of April 5, 2000 (the "Effective Date") by and between
                                                 --------------
Evercom, Inc., a Delaware corporation (previously known as Talton Holdings,
Inc.) (the "Company") and Donald B. Vaello (the "Executive").
            -------                              ---------

                                R E C I T A L S

     WHEREAS, the Company and Executive entered into an Employment Agreement,
dated as of June 26, 1998 (the "Agreement"); and
                                ---------

     WHEREAS, the Company and Executive wish to amend the Agreement;

     NOW, THEREFORE, in consideration of the promises and mutual agreements set
forth below, the parties hereby agree as follows.  All terms defined in the
Agreement will have the same meaning in this Amendment.

     1.  EMPLOYMENT PERIOD.  The date set forth on the first sentence of Section
         -----------------
2 shall be "March 31, 2003."  The date set forth in the second sentence of
Section 2 shall be "April 1, 2003."

     2.  POSITION AND DUTIES.  Section 3 of the Agreement shall be amended to
         -------------------
add the following sentence at the end of Section 3:

     The Executive shall be the Company's President and Chief Operating Officer,
     unless and until his title and duties are changed by the Company's Board of
     Directors.

     3.  COMPENSATION AND RELATED MATTERS.
         --------------------------------

          (a) Section 4(a), (b) and (c), relating to the Executive's Base
     Salary, Bonus and Options, are hereby amended in their entirety as set
     forth on Exhibit A attached to this Amendment.
              ---------

          (b) Section 4(e) is hereby amended in its entirety as follows:

               (e) RELOCATION.  The Executive shall relocate his primary
          residence to the Dallas-Fort Worth, Texas area if, and within a
          reasonable

                                     - 1 -
<PAGE>

          time after, Employee has been elected to the position of the Company's
          Chief Executive Officer. Upon termination of the Executive's
          employment for any reason, the Executive shall be reimbursed for
          reasonable out-of-pocket expenses (not including the cost of housing)
          incurred by the Executive in relocating his primary residence to the
          San Antonio, Texas area (or to another area of reasonably similar
          distance from the Dallas-Fort Worth, Texas area).

     4.   TERMINATION.  The second sentence of Section 5(b) shall be amended in
          -----------
its entirety as follows:

     If the Company terminates the Executive's employment without Cause prior to
     the expiration of the Employment Period, of if either party gives a notice
     not to extend this Agreement for a Renewal Period, the Company's liability
     to the Executive is limited to an amount equal to the Executive's annual
     Base Salary (the "Severance Payment").
                       -----------------

     5.   This Agreement, as amended by this Amendment, is ratified and
confirmed.

     6.   This Amendment shall be binding upon and shall inure to the benefit of
the parties hereto, their heirs, personal representatives, successors and
assigns.

     IN WITNESS WHEREOF, the parties have executed this Amendment as of the date
first written above.


COMPANY:                                        EXECUTIVE:
-------                                         ---------

Evercom, Inc.,
a Delaware corporation                          /s/ DONALD B. VAELLO
                                                -------------------------
                                                DONALD B. VAELLO
By: /s/ TERRY MATLACK
   ---------------------------
Name: TERRY MATLACK
Title: Chief Executive Officer

                                     - 2 -
<PAGE>

                                   EXHIBIT A
                                   ---------



(a)  Base Salary:  $275,000 per year.
     -----------

(b)  Bonus:        Bonus program to be established whereby Executive could earn
     -----
                   an additional amount up to 100% of Base Salary based upon
                   achieving performance objectives to be determined and may be
                   increased to as much as 200% of Base Salary in the event such
                   objectives are exceeded.

(c)  Options:      Executive will be eligible to participate in the Company's
     -------
                   stock option program, and subject to Board approval, will be
                   awarded options to purchase the equivalent to 300 common
                   shares of Company stock (being an increase of 100 shares over
                   the number set forth in the Agreement), having a strike price
                   equal to the fair market value of the Company's common stock
                   on the date of issuance of the options. Such options shall be
                   subject to such vesting requirements as are established by
                   the Board.


                            EXHIBIT A - Page 1 of 1
                            ---------