GUARANTEE ASSUMPTION AGREEMENT GUARANTEE ASSUMPTION AGREEMENT dated as of January 2, 1998 by ITDS Intelicom Services, Inc., a Delaware corporation (the "Additional Subsidiary Guarantor"), in favor of Lehman Commercial Paper Inc. ("LCPI"), as administrative agent for the lenders or other financial institutions or entities party as "Lenders" to the Credit Agreement referred to below (in such capacity, together with its successors in such capacity, the "Administrative Agent"). International Telecommunication Data Systems, Inc., a Connecticut corporation, the Subsidiary Guarantors referred to therein and the Administrative Agent are parties to a Credit Agreement dated as of January 2, 1998 (as modified and supplemented and in effect from time to time, the "Credit Agreement"). Pursuant to Section 9.17(a) of the Credit Agreement, the Additional Subsidiary Guarantor hereby agrees to become a "Subsidiary Guarantor" for all purposes of the Credit Agreement, and a "Debtor" for all purposes of the Security Agreement. Without limiting the foregoing, the Additional Subsidiary Guarantor hereby, jointly and severally with the other Subsidiary Guarantors, guarantees to each Lender, the Administrative Agent, Guarantors, guarantees to each Lender, the Administrative Agent, LCPI and the Arranger and their respective successors and assigns the prompt payment in full when due (whether at stated maturity, by acceleration or otherwise) of all Guaranteed Obligations (as defined in Section 6.01 of the Credit Agreement) in the same manner and to the same extent as is provided in Section 6 of the Credit Agreement. In addition, the Additional Subsidiary Guarantor hereby makes the representations and warranties set forth (i) in Sections 8.01, 8.02, 8.04, 8.07, 8.08, 8.09, 8.10, 8.11, 8.12, 8.13, 8.14 and 8.15 of the Credit Agreement, and in Section 2 of the Security Agreement, with respect to itself and its obligations under this Agreement, as if each reference in said Sections to the Basic Documents included reference to this Agreement, (ii) in Sections 8.16 and 8.17 of the Credit Agreement with respect to the supplements to Schedules I and III to the Credit Agreement attached hereto as Appendix A and (iii) in Section 2 of the Security Agreement with respect to the supplements to Annexes 1 through 6 to the Security Agreement attached hereto as Appendix B. The Additional Subsidiary Guarantor hereby agrees to take promptly such action (including, without limitation, delivering such shares of stock, executing and delivering such Uniform Commercial Code financing statements) as shall be necessary to create and perfect valid and enforceable first priority Liens on substantially all of its personal Property as collateral security for its obligations under the Credit Agreement. IN WITNESS WHEREOF, the Additional Subsidiary Guarantor has caused this Guarantee Assumption Agreement to be duly executed and delivered as of the day and year first above written. ITDS INTELICOM SERVICES, INC. By: /S/ Peter P. Bassermann ------------------------------ Title: President and Treasurer ACCEPTED AND AGREED: LEHMAN COMMERCIAL PAPER INC., as Administrative Agent By: /S/ Dennis J. Dee --------------------------- Title: Authorized Signatory -2- Appendix A to Guarantee Assumption Agreement Supplement to Schedule I of the Credit Agreement (Material Agreements and Liens): Part A: None Part B: UCC Filings for Leased Equipment Supplement to Schedule III of the Credit Agreement (Subsidiaries and Investments): Part A: None Part B: None Guarantee Assumption Agreement ------------------------------ -3- Appendix B to Guarantee Assumption Agreement Supplement to Annex 1 of the Security Agreement PLEDGED STOCK ------------- [See Section 2 (b) and (c) of the Security Agreement.] ITDS Intelicom Services, Inc. - ----------------------------- Certificate Registered Issuer Nos. Owner Number of Shares ------ ---- ----- ---------------- N/A N/A N/A N/A Annex 1 to Security Agreement ----------------------------- -4- Supplement to Annex 2 to the Security Agreement LIST OF COPYRIGHTS, COPYRIGHT REGISTRATIONS AND APPLICATIONS FOR COPYRIGHT REGISTRATIONS [See Section 2 (d) of the Security Agreement.] ITDS Intelicom Services, Inc. - ----------------------------- Date Registration Date of Title Registered No. Creation ----- ---------- ----------- -------- TRIS + front end February 11, 1993 TX 3653494 1993 TRIS + back end February 11, 1993 TX 3484231 1991 Annex 2 to Security Agreement ----------------------------- -5- Supplement to Annex 3 to the Security Agreement LIST OF PATENTS AND PATENT APPLICATIONS [See Section 2 (d) of the Security Agreement.] ITDS Intelicom Services, Inc. - ----------------------------- File Patent Country Registration No. Date - ---- ------ ------- ---------------- ---- NONE Annex 3 to Security Agreement ----------------------------- -6- Supplement to Annex 4 to the Security Agreement LIST OF TRADE NAMES, TRADEMARKS, SERVICES MARKS, TRADEMARK AND SERVICE MARK REGISTRATIONS AND APPLICATIONS FOR TRADEMARK AND SERVICE MARK REGISTRATIONS [See Section 2 (d) of the Security Agreement.] U.S. Trademarks --------------- ITDS Intelicom Services, Inc. - ----------------------------- Application (A) Registration (R) Registration Mark or Series No. (S) or Filing Date ---- ----------------- -------------- TRIS + R 1,842,753 July 5, 1994 TRIS Common Law Trademark Annex 4 to Security Agreement ----------------------------- -7- Foreign Trademarks ------------------ ITDS Intelicom Services, Inc. - ----------------------------- Application (A) Registration or Mark Registration (R) Country Filing Date (F) - ---- ---------------- ------- --------------- NONE Annex 4 to Security Agreement ----------------------------- -8- Supplement to Annex 5 to the Security Agreement LIST OF CONTRACTS, LICENSES AND OTHER AGREEMENTS [See Section 2 (d), (e) and (f) of the Security Agreement] ITDS Intelicom Services, Inc. - ----------------------------- ITDS Intelicom Services, Inc., uses licenses of various off-the-shelf business software and various public domain/share-ware software. It also licenses Intellectual Property to the following entities: Liberty Cellular/Kansas Cellular Southwestern Bell Mobile Southwestco/Bell Atlantic Mobile Mercury-Magnolia Mercury-Alaska 3 Cellcom/New Cell MobileTel Sagir NE Michigan/RFB Cellular Cybertel-Kauai NE Colorado Commnet Nextel Citizens Mohave Western Wireless Mid-Tex Cellular OneComm Dial Call Southern Company Omnipoint and, through a predecessor in interest, it licenses certain Intellectual Property to Sema Group Mobile Communications, Limited. ITDS Intelicom Services, Inc. has software license agreements and/or maintenance agreements with the following entities: Computer Associates Lotus Microsoft Select Microsoft Exchange McAfee Annex 5 to Security Agreement ----------------------------- -9- Supplement to Annex 6 to the Security Agreement LIST OF LOCATIONS [See Section 5.07 of the Security Agreement.] ITDS Intelicom Services, Inc. - ----------------------------- 2109 Fox Drive, Champaign IL 6707 Democracy Boulevard, Suite 1000 Bethesda, MD Annex 6 to Security Agreement ----------------------------- -10-