Recorded at the Request of:
Land Title Guarantee Company

When Recorded Mail to:

PILLSBURY MADISON & SUTRO LLP
P.O. Box 7880
San Francisco, CA 94120-7880
Attn:  Laura E. Hannusch, Esq.



                      ASSUMPTION AND MODIFICATION AGREEMENT


     THIS ASSUMPTION AND MODIFICATION AGREEMENT ("Agreement") is entered into as
of the  1st day of May  1999,  by and  among  ICG  SERVICES,  INC.,  a  Delaware
corporation  ("Grantor"),  whose address is 161 Inverness Drive West, Englewood,
Colorado 80112, ICG 161, L.P., a Delaware limited partnership ("Grantee"), whose
address is 161  Inverness  Drive West,  Englewood,  Colorado  80112,  and TRINET
REALTY CAPITAL,  INC., a Maryland  corporation  ("Lender")  whose address is One
Embarcadero Center, 33rd Floor, San Francisco, California 94111.

                              W I T N E S S E T H:

     WHEREAS,  Grantor is the owner of certain real property located in Arapahoe
County,  Colorado, more particularly described in Exhibit A attached hereto (the
"Premises"); and

     WHEREAS, Lender previously made a loan to Grantor in the original principal
amount of thirty-three  million  seventy-six  thousand seven hundred  fifty-four
dollars  ($33,076,754) (the "Loan"),  which Loan is evidenced by a Note executed
by Grantor in favor of Lender dated as of January 1, 1999,  in the amount of the
Loan (the "Note"),  and which Note is secured by, among other things,  a Deed of
Trust,  Assignment of Rents and Security  Agreement  dated as of January 1, 1999
(as amended from time to time, the "Deed of Trust"),  encumbering  the Premises,
executed  by  Grantor,  in favor  of the  Public  Trustee  of  Arapahoe  County,
Colorado,  as trustee, for the benefit of Lender, said Deed of Trust recorded in
the  Official   Records  of  Arapahoe   County,   Colorado,   as  Reception  No.
_________________; and

     WHEREAS, Lender is the owner and holder of the indebtedness and obligations
secured by the Deed of Trust (the "Secured Indebtedness"); and

     WHEREAS, Grantor is the current owner of the Premises; and

     WHEREAS,  Grantor  wishes to convey the Premises to Grantee  subject to the
Deed of Trust; and
<PAGE>

     WHEREAS, the Deed of Trust prohibits Grantor from conveying the Premises to
Grantee without the prior written consent of Lender; and

     WHEREAS,  Lender is willing to consent to the  proposed  conveyance  of the
Premises to Grantee and the  assumption by Grantee of the Secured  Indebtedness,
subject to certain  terms and  conditions,  including  but not  limited to those
terms and conditions set forth herein;

     NOW, THEREFORE, in consideration of the provisions hereof, as an inducement
to cause Lender to consent to the proposed  conveyance,  and for other  valuable
consideration,  the receipt and  sufficiency  of which are  acknowledged,  it is
agreed as follows:

     (A) Capitalized terms used herein,  but not otherwise  defined,  shall have
the meaning given them in the Deed of Trust.

     (B)  Consent to  Transfer.  Lender  hereby  consents to the  conveyance  by
Grantor to Grantee of Grantor's  interest in the  Premises.  Except as expressly
provided  herein or in the Loan  Documents (as defined  below),  such consent by
Lender  shall not  constitute  a consent  to any  further  or  subsequent  sale,
transfer, disposition or encumbering of any kind whatsoever, by deed of trust or
otherwise,  of the Mortgaged Property,  or any part thereof or interest therein,
or waive the necessity of further  consent from Lender  whenever such consent is
required pursuant to the Loan Documents.

     (C) Amount of Indebtedness.  Lender warrants,  as of the date hereof,  that
the outstanding principal balance under the Note is $33,076,754 and that Grantor
is not in default under the Loan Documents.

     (D) Assignment of the Loan;  Assumption by Grantee.  Effective as of May 1,
1999 (the  "Transfer  Date"),  Grantor  assigns to Grantee all of such Grantor's
obligations,  rights,  powers,  equities,  remedies,  and  interests in, to, and
arising out of the Loan,  together with the Loan Documents,  to have and to hold
the obligations,  rights, powers,  equities,  remedies, and interests of Grantor
in,  to,  and  arising  out of the Loan and Loan  Documents  unto  Grantee,  its
permitted  successors  and  assigns,  from and after the date hereof for all the
remaining  duration  of the Loan,  subject  to the  covenants,  conditions,  and
provisions  of such Loan as provided  in the Note and the other Loan  Documents.
Effective as of the Transfer Date,  Grantee assumes Grantor's  liability for the
payment of the Secured  Indebtedness  and all of the obligations of Grantor with
respect to the Loan,  including but not limited to the  obligations set forth in
the following documents executed in connection therewith:

          (i) Note;

          (ii) Deed of Trust; and

                                       2
<PAGE>

          (iii)  Assignment  of Leases  and Rents and other  Income  dated as of
     January 1, 1999, from Grantor, as assignor, to Lender, as assignee.

(The  foregoing  documents,  together  with  any  other  documents  executed  in
connection  with the Loan,  being herein  collectively  referred to as the "Loan
Documents.")  Grantee shall not assume the obligations of Grantor under the Loan
Agreement or the Secured  Environmental  Indemnity,  each dated as of January 1,
1999 (collectively,  the "Restated Agreements"),  between Grantor and Lender, as
such  agreements  are being amended and restated and will be executed by Grantee
directly.  If Lender so  requests,  Grantee  shall  sign a new  promissory  note
containing the same terms and conditions and in the same principal amount of the
Note to further  evidence  Grantee's  liability  for the  payment of the Secured
Indebtedness  and Lender and Grantee shall exchange such new promissory note for
the Note.

     (E) Modification of Loan Documents.

     (i) It is understood  and agreed that,  effective as of the Transfer  Date,
Grantee shall be substituted  for Grantor in each of the Loan Documents and each
of the Loan  Documents  shall be modified to amend the term or terms  defined to
identify  Grantor,  such as "Maker" in the Note,  "Trustor" in the Deed of Trust
and  "Borrower"  in the other Loan  Documents,  so that all such terms  identify
Grantee effective as of the Transfer Date.

     (ii)  Section  1.19 of the Deed of Trust is hereby  amended  by adding  the
following language at the end of such Section 1.19:

          ATrustor shall deliver to  Beneficiary,  within  forty-five  (45) days
          after  the end of each  fiscal  quarter,  income  statements,  balance
          sheets and statements of cash flow of ICG Services, Inc. ("Guarantor")
          and  its  Subsidiaries  (as  defined  in  the  Loan  Agreement),  on a
          consolidated basis, for such quarter, and a certificate of compliance,
          signed by an officer of  Guarantor,  certifying  the  accuracy of such
          statements and Guarantor's  compliance with its obligation to maintain
          at the end of each fiscal  quarter a Tangible Net Worth (as defined in
          the Loan Agreement) of at least fifty million  dollars  ($50,000,000).
          In  addition,   Trustor  shall  deliver  to  Beneficiary  as  soon  as
          practicable,  but in any event no later  than one  hundred  five (105)
          days after each fiscal year,  an income  statement,  balance sheet and
          statement  of  cash  flow of  Guarantor  and  its  Subsidiaries,  on a
          consolidated basis, for such fiscal year, all certified as to accuracy
          by an independent  certified public  accountant or  representative  of
          Guarantor  reasonably  acceptable to  Beneficiary.  All such financial


                                       3
<PAGE>

          statements  shall be prepared in accordance  with  generally  accepted
          accounting principles  consistently applied. Such financial statements
          shall be in form and detail reasonably satisfactory to Beneficiary."

     (iii)  Section  1.21 of the Deed of  Trust  is  hereby  amended  by  adding
"(except  with respect to a transfer  described in Section 5.14  hereof)"  after
"any  interest  in the  Mortgaged  Property"  and  before  ", of if there is any
change. . ."

     (iv) The Deed of Trust is hereby  modified  by adding a new  Section  5.14,
which reads as follows:

          "5.14 Partial Release. As of May 4, 1999, Trustor,  Beneficiary,  TEFX
     and Tenant have entered into that certain Agreement  Regarding  Subdivision
     (the  "Subdivision  Agreement"),  whereby the parties  thereto  have agreed
     that, at the request of either  Beneficiary or Tenant, the Property will be
     subdivided,  with the portion of the  Property  currently  improved  with a
     building and parking facilities (the "Improved Parcel") forming one parcel,
     and the  "Expansion  Site"  determined in accordance  with the  Subdivision
     Agreement  forming a second  parcel,  all on the terms and  conditions  set
     forth in the Subdivision  Agreement.  In such case and upon satisfaction of
     all of the conditions set forth in the Subdivision  Agreement,  Beneficiary
     shall  release,  or direct the Trustee to release,  the Expansion Site from
     the lien of this Deed of Trust.  All  expenses of  Beneficiary  and Trustee
     incurred in connection  with  preparing,  negotiation  and  recording  such
     release documents,  and the cost of any endorsement to Beneficiary's  title
     insurance  policy  reasonably  required  by  Beneficiary,  shall be paid by
     Trustor, as set forth in the Subdivision Agreement."

     (F) The  effectiveness of this Agreement and the consents granted by Lender
are conditioned on delivery to Lender of:

          (i) An Amended and Restated  Loan  Agreement,  in form  acceptable  to
     Lender, dated as of May 4, 1999, executed by Grantee;

          (ii) An Unsecured Environmental  Indemnity (the "Indemnity"),  in form
     acceptable  to Lender,  dated as of May 4, 1999,  executed  by Grantor  and
     Grantee; and

          (iii) A Continuing  Guaranty (the  "Guaranty"),  in form acceptable to
     Lender, dated as of May 4, 1999, executed by Grantor.

     (G) Release.  Effective as of the Transfer Date,  Lender  releases  Grantor
from any and all  liability  and  obligation  under the Loan  Documents  and the
Restated Agreements,  and each of them, but not from the documents referenced in
paragraphs (F)(ii) and (iii) of this Agreement.

                                       4
<PAGE>

     (H)  Modifications  and  Renewals.  Lender  may  hereafter  enter  into any
modification,  extension or renewal of the Secured Indebtedness with the consent
of Grantee  alone,  and  Grantor  hereby  waive  notice of any of the same.  Any
renewal  notes,   modification  or  extension   agreements  or  other  documents
pertaining to the Secured  Indebtedness may hereafter be entered into by Grantee
without the joinder of Grantor and without limiting the liability of Grantor for
payment of the Secured Indebtedness pursuant to the Guaranty or the Indemnity.

     (I)  Estoppels.  Grantor  hereby  certifies and confirms for the benefit of
Lender, the following:

          (i) The Loan Documents are in full force and effect.

          (ii) Lender has complied with all terms,  conditions and provisions of
     the Loan Documents to be complied with by Lender, and no event has occurred
     and no  circumstance  exists  that  would,  with the passage of time or the
     giving of notice,  or both,  constitute  a default by Lender under the Loan
     Documents.  There is no existing  basis for Grantor to exercise  any remedy
     available to it by virtue of a default or other action by Lender.

          (iii)  There  are no  charges,  liens,  defenses,  offsets,  claims or
     credits  known or asserted by Grantor  against the  payments  due under the
     Note or other sums due  Lender or  against  the  performance  of  Grantor's
     obligations under the Loan Documents.

          (iv) There are no pending suits, proceedings, judgments, bankruptcies,
     liens or executions  against Grantor or any affiliate of Grantor that could
     adversely affect the Premises.

     (J) Representations and Warranties.  Grantee hereby represents and warrants
for the benefit of Lender, the following:

          (i)  Grantee is a Delaware  limited  partnership,  is duly  formed and
     validly  existing  under the laws of the State of Delaware and is qualified
     to  do  business  in  the  State  of   Colorado.   Grantee's   federal  tax
     identification number is 84-1448147.

          (ii) Grantee has full power and authority to enter into this Agreement
     and to perform this Agreement.  The execution,  delivery and performance of
     this  Agreement  by Grantee  have been duly and validly  authorized  by all
     necessary  action on the part of  Grantee  and all  required  consents  and
     approvals have been duly obtained.

                                       5
<PAGE>

          (iii) This  Agreement  is a legal,  valid and  binding  obligation  of
     Grantee, enforceable against Grantee in accordance with its terms.

     (K) No  Marshalling  of  Assets.  Lender  may  proceed  against  collateral
securing the Secured  Indebtedness  and against  parties liable therefor in such
order as it may  elect,  and  neither  Grantor  nor  Grantee  nor any  surety or
guarantor for either of them nor any creditor of either Grantor or Grantee shall
be entitled to require Lender to marshall assets. The benefit of any rule of law
or equity to the contrary is hereby expressly waived.

     (L) Impairment of Collateral.  Lender may, in its sole discretion,  release
the Deed of Trust or any other collateral  securing the Secured  Indebtedness or
release any party liable therefor.  The defenses of impairment of collateral and
impairment  of recourse and any  requirement  of  diligence on Lender's  part in
collecting the Secured Indebtedness are hereby waived.

     (M) Amendment and Waiver in Writing.  No provision of this Agreement can be
amended or waived,  except by a  statement  in writing  signed by all parties to
this Agreement.

     (N) Assignment.  This Agreement and all related  documents shall be binding
upon and inure to the benefit of the respective heirs, successors and assigns of
Grantor, Grantee and Lender.

     (O) Entire  Agreement.  This Agreement and the documents  referenced herein
and those executed  concurrently  herewith  represent the entire agreement among
the parties concerning the Loan.

     (P)  Severability.  Should any  provision  of this  Agreement be invalid or
unenforceable  for any reason,  the remaining  provisions hereof shall remain in
full effect.

     (Q) Applicable Law. The validity and construction of this Agreement and all
other  documents  executed  with  respect to the Secured  Indebtedness  shall be
determined  according to the laws of Colorado  applicable to contracts  executed
and performed within that state.

     (R) Gender and Number.  Words used herein indicating gender or number shall
be read as context may require.

     (S) Captions Not  Controlling.  Captions and headings have been included in
this Agreement for the convenience of the parties, and shall not be construed as
affecting the content of the respective paragraphs.

                                       6
<PAGE>

     (T) Counterparts.  This Agreement may be executed by counterpart  signature
pages,  and it shall not be  necessary  that the  signatures  of all  parties be
contained on any one counterpart.  Each counterpart shall be deemed an original,
but all of them together shall constitute one and the same instrument

     Executed the date first written above.

THE  UNDERSIGNED  ACKNOWLEDGE  A  THOROUGH  UNDERSTANDING  OF THE  TERMS OF THIS
AGREEMENT AND AGREE TO BE BOUND THEREBY:

                         GRANTOR:

                         ICG SERVICES, INC., a Delaware corporation



                         By  /s/ H. Don Teague
                             ----------------------------------
                              Its  Executive Vice President
                                   ----------------------------



                         GRANTEE:

                         ICG 161, L.P., a Delaware limited partnership

                         By    ICG CORPORATE HEADQUARTERS, L.L.C., a Colorado
                         limited liability company, its general partner

                         By   ICG SERVICES, INC., a Delaware corporation,
                         its manager

                         By  /s/ H. Don Teague
                             ----------------------------------
                              Its   Executive Vice President
                                    ---------------------------

                         LENDER:

                         TRINET REALTY CAPITAL, INC., a Maryland corporation


                         By
                             ----------------------------------
                              Its
                                    ---------------------------

                                       7
<PAGE>

STATE OF Colorado             )
                              ) ss.
CITY AND COUNTY OF Denver     )


     The foregoing  instrument was acknowledged  before me this 13th day of May,
1999,  by H. Don Teague as Executive  Vice  President of ICG  SERVICES,  INC., a
Delaware corporation.

         My commission expires:  1/3/2000

         Witness my hand and official seal.


                                        /s/  Elizabeth G. Gashins
                                        -------------------------
                                              Notary Public



STATE OF Colorado             )
                              ) ss.
CITY AND COUNTY OF Denver     )


     The foregoing  instrument was acknowledged  before me this 13th day of May,
1999, by H. Don Teague as Executive  Vice  President of ICG Services,  Inc., the
general partner of ICG 161, L.P., a Delaware limited partnership.

         My commission expires:  1/3/2000

         Witness my hand and official seal.


                                       /s/  Elizabeth G. Gashins
                                       -------------------------
                                             Notary Public




<PAGE>
     (T) Counterparts.  This Agreement may be executed by counterpart  signature
pages,  and it shall not be  necessary  that the  signatures  of all  parties be
contained on any one counterpart.  Each counterpart shall be deemed an original,
but all of them together shall constitute one and the same instrument

     Executed the date first written above.

THE  UNDERSIGNED  ACKNOWLEDGE  A  THOROUGH  UNDERSTANDING  OF THE  TERMS OF THIS
AGREEMENT AND AGREE TO BE BOUND THEREBY:

                         GRANTOR:

                         ICG SERVICES, INC., a Delaware corporation



                         By
                             ----------------------------------
                              Its
                                   ----------------------------



                         GRANTEE:

                         ICG 161, L.P., a Delaware limited partnership

                         By    ICG CORPORATE HEADQUARTERS, L.L.C., a Colorado
                         limited liability company, its general partner

                         By   ICG SERVICES, INC., a Delaware corporation,
                         its manager

                         By
                             ----------------------------------
                              Its
                                    ---------------------------

                         LENDER:

                         TRINET REALTY CAPITAL, INC., a Maryland corporation


                         By  /s/ Kevin E. Deeble
                             ----------------------------------
                              Its   Vice President
                                    ---------------------------


                                       7
<PAGE>

STATE OF California       )
                          ) ss.
COUNTY OF San Francisco   )


         The foregoing  instrument was  acknowledged  before me this 12th day of
May, 1999, by  Kevin E. Deeble  as Vice President of TRINET REALTY
CAPITAL, INC., a Maryland corporation.

         My commission expires:  November 7, 2002

         Witness my hand and official seal.


                                         Mary Sainsbury
                                    --------------------------
                                          Notary Public


<PAGE>

                                    EXHIBIT A
                                LEGAL DESCRIPTION


     All  that  certain  real  property  in the  County  of  Arapahoe,  State of
Colorado, described as follows:

LOT 1,  INVERNESS  SUBDIVISION  FILING  NO.  22,  COUNTY OF  ARAPAHOE,  STATE OF
COLORADO