Exhibit 10
                                                             June 27, 1997
  Mr. George Conrades
  3 Channing Place
  Cambridge, MA  02138
  
  Dear George:
  
  I want to let you know how pleased and excited I am that you will continue 
  to lead BBN Corporation ("BBN") as it integrates with the data strategy of 
  GTE Corporation ("GTE").  I am confident that, with you as part of the GTE 
  team, we will be better able to take on the many challenges, and take 
  advantage of the many opportunities, that face us.  We have constructed a 
  compensation package as described in this letter ("Letter Agreement") which 
  recognizes your value to our data business and which will reward you based 
  on your contributions, the success of the data business, and the success of 
  GTE.
  
  Term of Letter Agreement:  Subject to the early termination provisions 
  described below, the term of this Letter Agreement will begin on July 1, 
  1997 and end on June 30, 1999 (the "Term").  The Term may be extended by 
  mutual written agreement. 
  
  Position:  Your position will be Executive Vice President and President - 
  Data, GTE Corporation, and you will report to me.  Your principal office 
  will be located in the greater Dallas, Texas area.    
  
  Base Salary:  You will receive an annual base salary of $450,000.  You will 
  be on the GTE Service Corporation ("Service Corp.") payroll.  
  
  Executive Incentive Plan:  You will participate in GTE's Executive Incentive 
  Plan ("EIP") as if you were employed for the full 1997 calendar year in 
  accordance with the terms of the EIP.  For 1997, the anticipated EIP payout 
  range for your position will be a norm of $211,500 and a maximum (200% of 
  norm) of $423,000.  The target bonus is typically 130% of norm, or in your 
  case, $274,950.  For illustrative purposes, a bonus opportunity with a 
  payout at 150% of the norm would provide you with a bonus of $317,250 for 
  the full 1997 calendar year.  Recommended payouts for EIP awards are based 
  on your actual performance, the performance of your business unit, and the 
  performance of GTE and its affiliates (the "Company") and are subject to the 
  approval of the Executive Compensation and Organizational Structure 
  Committee ("ECC") of the GTE Board of Directors (the "Board").  Subject to 
  the EIP deferral regulations, awards typically are paid in the first quarter 
  of the following calendar year. 
  
  Long-Term Incentive Plan:  You will participate in GTE's Long-Term Incentive 
  Plan ("LTIP") which provides for stock option grants and performance bonus 
  awards (collectively referred to herein as "LTIP Grants").
  
      a.   Stock Options.  On or about July 1, 1997, you will be granted an 
  option to purchase 75,000 shares of GTE common stock.  In addition, in each 
  of 1998 and 1999, you will be eligible for a grant of a stock option which, 
  at your current level, typically would be to purchase approximately 62,200 
  shares of GTE common stock.  The exercise price per share for each option 
  <PAGE>
  described in this paragraph will be based on the average of the high and low 
  price of GTE common stock on the New York Stock Exchange composite tape on 
  the date each grant is approved by the ECC.  Each grant will vest on a 
  one-third per year basis over a period of three years from the grant date.  
  If you separate from employment at the end of the Term, you will have five 
  years from your separation date to exercise your GTE stock options which are 
  or become vested during that five-year period, but in no event more than ten 
  years from the date of the grant ("Special Exercise Period"). 
  
      b.   Performance Bonus Awards.  Effective on the date you become 
  employed by Service Corp., you will be eligible for participation in the 
  following outstanding LTIP performance bonus award cycles, 1995-1997, 
  1996-1998, and 1997-1999, as though you were employed by Service Corp. on 
  the first day of each outstanding award cycle.  As such, you will receive 
  the following number of performance units for each award cycle:  1995-1997 - 
  5,900 units, 1996-1998 - 7,400 units, and 1997-1999 - 7,400 units.  
  Performance in the LTIP is based on achievement of financial objectives by 
  the Company over a three-year period.  Subject to the LTIP deferral 
  regulations, payment typically is made during the first quarter of the year 
  following the last year of the award cycle.  Actual payment for each cycle 
  will depend on actual Company performance, the accumulation of dividend 
  equivalents, and the value of GTE common stock and is subject to ECC 
  approval.   
  
  The ECC has the sole discretion to determine the amount, if any, of an LTIP 
  Grant to an executive, as well as the value of any payment with respect to 
  any Performance Bonus Award.  Of course, you will be treated in the same 
  manner as other similarly situated senior executives of Service Corp. with 
  respect to LTIP Grants.   
  
  Special Bonus:  In addition to the LTIP performance bonus opportunities 
  described above, you will be eligible for a special performance bonus 
  opportunity based on specific performance measures as follows: revenue 
  growth, operating income, net income, capital expenditures, operating cash 
  flow, and return on investment for GTE's data business ("Special Bonus").  
  The target payment for the Special Bonus is $250,000 per fiscal year, and I 
  will be responsible for determining whether the performance targets for the 
  Special Bonus have been met.  For purposes of the Special Bonus, a "fiscal 
  year" commences July 1 and ends June 30, and the first fiscal year will 
  commence July 1, 1997 and end June 30, 1998.  The maximum payment for a 
  fiscal year is $500,000, and, of course, for each performance measure no 
  payment will be made if certain performance targets are not met.  You will 
  be provided with more details regarding the Special Bonus under separate 
  cover within the next few days.  The Special Bonus is eligible for deferral 
  but is not eligible for the Equity Participation Program (as described in 
  the immediately succeeding paragraph). 
  
  Savings/Deferred Compensation Opportunities:  You will be eligible to 
  participate in the GTE Savings Plan and the GTE Executive Salary Deferral 
  Plan in accordance with the plan provisions.  These provisions are described 
  in booklets being sent to you under separate cover.
  
  GTE's EIP and LTIP deferral programs allow for up to 100 percent deferral of 
  awards to some pre-selected date in the future.  In addition, GTE recently 
  has introduced a new feature, the "Equity Participation Program" ("EPP"), 
  which, at your level will require a mandatory deferral of a specified 
  percentage of your combined EIP and LTIP awards into GTE restricted stock 
  <PAGE>
  units.  If, for example, your combined EIP and LTIP awards equal more than 
  $400,000 and not more than $800,000, the required deferral percentage will 
  be 20%, and if your combined EIP and LTIP awards equal more than $800,000, 
  the required deferral percentage will be 25%.  GTE will match deferrals 
  under the EPP on a one-for-four basis, subject to certain forfeiture 
  provisions.  
  
  Pension Benefits/Executive Retired Life Insurance Plan ("ERLIP"):  You will 
  be eligible to participate in the Service Corp. basic pension plan and the 
  Supplemental Executive Retirement Plan ("SERP").  However, if you terminate 
  employment with the Company before you meet the plans' generally applicable 
  vesting requirements (generally, five years of service), you will not be 
  entitled to receive any benefits from the plans.  If, during the Term, any 
  enhanced retirement benefits are offered to employees pursuant to the basic 
  pension plan, the SERP, or otherwise in connection with a voluntary or 
  involuntary separation or retirement program, you will not be eligible for 
  such enhanced benefits.  Moreover, you will only be eligible for ERLIP 
  benefits if you separate from employment with the requisite number of years 
  of service (generally, ten years).
  
  Other Benefit Plans:  As a Service Corp. employee, you will be entitled to a 
  full range of benefits as detailed in the GTE CHOICES Benefits Program 
  Summary booklet being sent to you under separate cover. 
  
  Changes to Benefits and Compensation Plans/Summary of Terms:  As you 
  probably know, the Company reserves the right to modify or terminate any of 
  its benefit plans or compensation plans, including but not limited to any of 
  the executive benefit plans or compensation plans described in this letter.  
  You should know that this Letter Agreement is intended only as a brief 
  summary of the terms of the GTE benefit and compensation plans.  In the 
  event of any conflict with the description in this Letter Agreement and the 
  plan terms, the plan terms will control. 
  
  Vacation:  You will be entitled to four weeks of vacation annually.
  
  Perquisites:  You will receive perquisites provided to other executives at 
  your level in accordance with Service Corp. policy.  In addition, you will 
  receive the sum of $2,500 per month to cover the cost of maintaining an 
  apartment in Dallas during the Term.  During the Term, you also will receive 
  $1,000 per month as a car allowance, and you will be reimbursed for the 
  reasonable and customary expenses of one country club membership in either 
  the greater Boston or greater Dallas area (not including special assessments 
  in excess of $500 or personal, non-business expenses).  Finally, during the 
  Term, you will be reimbursed for reasonable travel expenses you incur for 
  travel between Cambridge, Massachusetts and Dallas, Texas, in accordance 
  with Service Corp. policy.    
  
  Intellectual Property:  As a Service Corp. employee, you must agree to 
  comply with the provisions of GTE's Intellectual Property Rights Agreement 
  and policies.  I am enclosing a copy of the Intellectual Property Rights 
  Agreement, which reflects those policies and which you will need to execute 
  on or before commencing employment. 
  
  Separation Benefit:  Since you already have an executive severance agreement 
  as described below, upon your separation from employment with the Company 
  during or at the end of the Term, you will not be eligible to participate in 
  any separation program sponsored by the Company whether payable from a 
  <PAGE>
  qualified plan or from the Company's general assets, other than the BBN 
  executive severance agreement and GTE Change in Control Agreement, both as 
  described below.  
  
  Executive Severance Agreement:  You agree that neither the offer nor the 
  acceptance of your new position as described in this Letter Agreement shall 
  constitute a triggering event for the receipt of severance benefits under 
  the Executive Severance Agreement between you and BBN, dated January 5, 1994 
  (the "Severance Agreement").  You further agree: that the Severance 
  Agreement shall remain in effect until June 30, 1999; that the Severance 
  Agreement applies only to those of your BBN benefits (including compensation 
  arrangements) that were in effect prior to the consummation of the GTE/BBN 
  tender offer on June 10, 1997; that the Severance Agreement will not apply 
  to any of the benefits and compensation arrangements described in this 
  Letter Agreement; and that by entering into this Letter Agreement, you 
  consent to an amendment of the Severance Agreement to so provide.  As we 
  have discussed, the significance of the Severance Agreement remaining in 
  effect until June 30, 1999 is that, if you separate from employment with GTE 
  on or before June 30, 1999, other than on account of your death, total 
  disability, or retirement after normal retirement date, and other than for 
  "Cause" as set forth in the Severance Agreement, such separation will 
  constitute a triggering event for the receipt of severance benefits under 
  the Severance Agreement.  
  
  You will be eligible for an executive Change in Control Agreement from GTE 
  ("Change in Control Agreement") which is similar to the change in control 
  agreements provided to other executives at your level; provided that any 
  payments or benefits payable pursuant to the Change in Control Agreement 
  will be reduced dollar for dollar by any payments or benefits paid to you or 
  which you are eligible to receive solely pursuant to the Severance 
  Agreement.
  
  Early Termination of Term:  In the event any of the following occurs prior 
  to the expiration of the Term, any salary earned through the date of 
  separation will be paid as soon as practicable following such separation and 
  you will receive no further salary; your EIP, LTIP performance bonus awards, 
  and the Special Bonus will be pro-rated to your date of separation (but 
  these bonuses will not be paid until the date they would otherwise have been 
  paid if any one of the events described below had not occurred); all 
  unvested options as of your separation date will be canceled; the Special 
  Exercise Period will be shortened if you separate prior to attaining age 60, 
  so that you will have one year from your separation date to exercise your 
  GTE stock options which are vested on the date of separation; your deferral 
  opportunities and other benefits will be determined in accordance with the 
  relevant plan documents; your entitlement to the perquisites will cease on 
  your date of separation; and you will not be entitled to any other 
  compensation or benefits:
  
      a.   You voluntarily separate from employment for any reason including
           as a result of invoking your Severance Agreement;
  
      b.   Your employment is terminated for "Cause";
  
      c.   You die; or
  
      d.   You become disabled (within the meaning of the Company's Long-Term
           Disability Plan).  
  <PAGE>
  For purposes of this Letter Agreement, "Cause" is defined as your commission 
  of a felony which is intended to result in your substantial personal 
  enrichment at the Company's expense, or your conviction of a crime involving 
  moral turpitude.
  
  In the unlikely event your employment is involuntarily terminated for 
  reasons other than those set forth in a-d above, this Letter Agreement will 
  remain in effect until the end of the Term.
  
  Of course, in the event of a Change in Control as defined in the Change in 
  Control Agreement, the provisions of that Change in Control Agreement will 
  apply.
  
  Applicable Law:  This Letter Agreement shall be construed in accordance with 
  the laws of the State of New York determined without regard to its choice of 
  law rules, and any disputes will be resolved by courts in the State of New 
  York.
  
  Entire Agreement:  Except as specifically provided in this Letter Agreement, 
  this Letter Agreement sets forth our entire understanding and supersedes any 
  prior agreement or understanding relating to your employment with GTE and 
  the matters contained in this Letter Agreement.  No amendment to this Letter 
  Agreement will be effective unless it is in writing and signed by both you 
  and GTE.
  
  George, as we discussed, we believe that GTE is well positioned to 
  capitalize on the significant opportunities which the merger with BBN has to 
  offer, in particular the enhancement of GTE's data strategy.  To help us get 
  there, we need you on the GTE team.  This letter presents what I consider to 
  be a very attractive employment offer.  I trust you agree and recognize that 
  if we can exceed our business targets, the compensation rewards will be 
  significant.  If any aspect of this letter raises questions, please contact 
  me or Randy MacDonald.  
  
  Please indicate your acceptance of this offer by signing below and return 
  the signed acceptance to me, retaining one copy for your records.
  
  Sincerely,
  
  Kent B. Foster
  
  I agree to the terms and conditions as set forth in this Letter Agreement 
  and accept the position of Executive Vice President and President - Data, 
  GTE Corporation.
  
  George Conrades                                        DATE: July 1, 1997
  
  cc: J. R. MacDonald
  bcc:  M.A. Cameron
        R.L. Campbell
        E.D. Singer