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                            CONTINUING LEASE GUARANTY

     THIS GUARANTY, made as of January 20, 1998, by ICG COMMUNICATIONS,  INC., a
Delaware  corporation  ("Guarantor") to TRINET  ESSENTIAL  FACILITIES X, INC., a
Maryland corporation ("Landlord").

                              W I T N E S S E T H:

     1. For valuable  consideration,  receipt of which is  acknowledged,  and to
satisfy  certain  requirements  under  the Lease  dated  January  15,  1998 (the
"Lease")  between  Landlord  and ICG  Holdings,  Inc.,  a  Colorado  corporation
("Tenant"),   Guarantor  hereby  absolutely,   unconditionally  and  irrevocably
guarantees to Landlord,  and agrees fully to pay, perform and discharge,  as and
when  payment,  performance  and  discharge  are  due,  all  of  the  covenants,
obligations  and  liabilities  of Tenant  under  the  Lease and all  amendments,
modifications, renewals, extensions, supplements, substitutions and replacements
of the Lease arising  during the period  beginning on the date hereof and ending
on the date this  Guaranty is terminated  (the  "Guaranteed  Obligations").  The
obligations of Guarantor  under this Guaranty  shall be absolute,  unconditional
and irrevocable and shall continue and remain in full force and effect until all
of the Guaranteed Obligations have been fully paid, performed and discharged.

     2. The  obligations of Guarantor under this Guaranty shall not be affected,
modified or impaired by the occurrence of any of the following  events,  whether
or not with notice to, or the consent of, Guarantor: (a) the waiver,  surrender,
compromise,  settlement,  release or termination of any or all of the Guaranteed
Obligations; (b) the failure to give notice to Guarantor of the occurrence of an
event of default under the Guaranteed Obligations; (c) the extension of the time
for  the  payment,  performance  or  discharge  of any or all of the  Guaranteed
Obligations;  (d) the amendment or modification  (whether material or otherwise)
of the Guaranteed Obligations in any respect; (e) any failure,  omission,  delay
or lack on the part of Landlord to enforce,  assert or exercise any right, power
or remedy  conferred  on  Landlord  under the  Guaranteed  Obligations;  (f) the
voluntary or involuntary liquidation,  dissolution, sale or other disposition of
all or substantially  all of the assets,  marshalling of assets and liabilities,
receivership,  insolvency,  bankruptcy, assignment for the benefit of creditors,
reorganization,  arrangement, composition with creditors or adjustment of debts,
or other similar proceedings  affecting Tenant or Guarantor or any of the assets
of either of them;  (g) the release or  discharge  by operation of law of Tenant
from the  payment,  performance  or  discharge  of any or all of the  Guaranteed
Obligations;  (h) the release or discharge by operation of law of Guarantor from
any or all of the  obligations  of  Guarantor  under this  Guaranty;  or (i) the
invalidity  or  unenforceability  of any or all of the  Guaranteed  Obligations.
Guarantor acknowledges that Landlord would not enter into the Lease without this
Guaranty and that Landlord is relying on this Guaranty.
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     3. The  obligations of Guarantor under this Guaranty are independent of the
Guaranteed  Obligations.  Guarantor agrees that Landlord shall have the right to
proceed  against  Guarantor  directly and  independently  of Tenant.  A separate
action may be brought and prosecuted  against Guarantor whether or not an action
is  brought  against  Tenant or Tenant is joined in any such  action.  Guarantor
authorizes  Landlord and Tenant,  without  notice to, demand of, or consent from
Guarantor and without  releasing or affecting  Guarantor's  liability under this
Guaranty,  from time to time to amend,  modify,  renew,  extend,  supplement  or
replace  the  Guaranteed  Obligations  or  otherwise  change  the  terms  of the
Guaranteed   Obligations,   to  take  and  hold  security  for  the   Guaranteed
Obligations, and to enforce, waive, surrender, impair, compromise or release any
such  security  or any or all of the  Guaranteed  Obligations  or any  person or
entity liable for any or all of the Guaranteed  Obligations.  Guarantor shall be
and remain bound under this Guaranty notwithstanding any such act or omission by
Tenant or Landlord.  Guarantor  waives the right, if any, to require Landlord to
proceed  against  Tenant,  to proceed  against or exhaust any  security  held by
Landlord, or to pursue any other remedy in Landlord's power. Landlord shall have
the right to exercise or enforce any right or remedy  Landlord  may have against
Tenant or any security held by Landlord.  Guarantor waives the right, if any, to
the benefit of, or to direct the  application of, any security held by Landlord.
Guarantor  waives (a) any defense  arising out of any alteration of the original
Guaranteed Obligations,  (b) any defense arising out of the absence,  impairment
or loss of any right of reimbursement or subrogation or other right or remedy of
Guarantor  against Tenant or any security held by Landlord,  and (c) any defense
arising by reason of any  disability  or other defense of Tenant or by reason of
the cessation or reduction from any cause  whatsoever of the liability of Tenant
other  than  full  payment,   performance   and  discharge  of  the   Guaranteed
Obligations.  The  cessation  or  reduction  of the  liability of Tenant for any
reason  whatsoever  other than full  payment,  performance  and discharge of the
Guaranteed  Obligations  shall not release or affect in any way the liability of
Guarantor under this Guaranty.

     4. If  Tenant  becomes  insolvent  or is  adjudicated  bankrupt  or files a
petition for  reorganization,  arrangement,  composition or similar relief under
any present or future  provision of the federal  Bankruptcy  Code,  or if such a
petition is filed against  Tenant,  or if Tenant makes a general  assignment for
the  benefit  of  creditors,  and  in  any  such  proceeding  any  or all of the
Guaranteed  Obligations  are  terminated  or  rejected  or  any  or  all  of the
Guaranteed  Obligations  are modified or abrogated,  then Guarantor  agrees that
Guarantor's  liability  under this  Guaranty  shall not  thereby be  affected or
modified  and such  liability  shall  continue in full force and effect as if no
such action or proceeding  had  occurred.  This  Guaranty  shall  continue to be
effective or be reinstated, as the case may be, if any payment of the Guaranteed
Obligations  must be returned by Landlord  upon the  insolvency,  bankruptcy  or
reorganization of Tenant or Guarantor,  or otherwise, as though such payment had
not been made.
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     5. Guarantor  assumes the  responsibility  for being and keeping  Guarantor
informed of the  financial  condition  of Tenant and of all other  circumstances
bearing  upon  the risk of  failure  to pay,  perform  or  discharge  any of the
Guaranteed Obligations which diligent inquiry would reveal, and Guarantor agrees
that Landlord has no duty to advise  Guarantor of information  known to Landlord
regarding such condition or any such circumstance.  Guarantor  acknowledges that
repeated and  successive  demands may be made and payments or  performance  made
hereunder  in response to such  demands as and when,  from time to time,  Tenant
defaults in the payment, performance or discharge of the Guaranteed Obligations.
Notwithstanding any such payments and performance hereunder, this Guaranty shall
remain  in full  force and  effect  and  shall  apply to any and all  subsequent
defaults  by Tenant.  It is not  necessary  for  Landlord  to  inquire  into the
capacity,  authority or powers of Tenant or the partners,  directors,  officers,
employees,  agents or  representatives  acting or purporting to act on behalf of
Tenant,  and all of the Guaranteed  Obligations made or created in reliance upon
the purported exercise of such powers shall be guaranteed under this Guaranty.

     6. If Tenant and Guarantor fail to pay, perform and discharge,  as and when
payment,  performance and discharge are due, all of the Guaranteed  Obligations,
Landlord shall have the right, but no obligation,  and without  releasing Tenant
or  Guarantor  from  any of the  Guaranteed  Obligations,  to pay,  perform  and
discharge  any or all of the  Guaranteed  Obligations  on behalf  of Tenant  and
Guarantor.  Guarantor  shall,  on demand,  pay to Landlord all sums  expended by
Landlord  in  the  payment,   performance   and  discharge  of  the   Guaranteed
Obligations,  together  with  interest  on  all  such  sums  from  the  date  of
expenditure  to the date  all such  sums are  paid by  Tenant  or  Guarantor  to
Landlord at the Interest  Rate (as defined in the Lease).  Guarantor  waives all
presentments,  demands for  performance,  notices of  nonperformance,  protests,
notices of  protest,  notices of  dishonor  and  notices of  acceptance  of this
Guaranty.  Guarantor agrees to pay all costs and expenses,  including reasonable
attorneys'  fees and  disbursements,  which  are  incurred  by  Landlord  in the
enforcement  of this  Guaranty.  If any provision of this Guaranty is held to be
invalid or unenforceable, the validity or enforceability of the other provisions
of this Guaranty shall not be affected. If there is more than one Guarantor, all
obligations  of  Guarantor  under this  Guaranty  shall be the joint and several
obligations of each  Guarantor.  This Guaranty may not be amended or modified in
any respect except by a written instrument signed by Guarantor and Landlord.  As
used in this  Guaranty,  the singular  shall  include the plural.  This Guaranty
shall  bind and  inure to the  benefit  of  Guarantor  and  Landlord  and  their
respective transferees, personal representatives, heirs, successors and assigns.
This Guaranty shall be governed by and construed in accordance  with the laws of
the  State  where the  premises  leased by Tenant  from  Landlord  are  located.
Guarantor hereby irrevocably  consents to the non-exclusive  jurisdiction of the
courts of the States of Colorado  and  California  and any federal  court of the
United States of America  located in the City of San Francisco,  California,  or
the city of Denver,  Colorado.  Guarantor  and Landlord  each waive any right to
trial by jury in connection  herewith.  Without limiting anything else contained
herein,  the  fullest  extent it may  effectively  do so under  applicable  law,
Guarantor  irrevocably  waives and agrees not to assert,  by way of motion, as a
defense or otherwise,  any claim that it is not subject to the  jurisdiction  of
any such court, any objection that it may now or hereafter have to the laying of
the venue of any such suit,  action or proceeding  brought in any such court and
any claim that any such suit, action or proceeding brought in any such court has
been brought in an inconvenient forum.
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     7. To induce  Landlord to enter into the Lease,  Guarantor  represents  and
warrants to Landlord as follows:  Guarantor is a corporation  existing under the
laws of the State of Delaware.  Guarantor  has full power and authority to enter
into this  Guaranty  and to perform its  obligations  under this  Guaranty.  The
execution, delivery and performance of this Guaranty by Guarantor have been duly
and validly  authorized by all necessary action on the part of Guarantor and all
required  consents and  approvals  have been duly  obtained.  This Guaranty is a
legal, valid and binding obligation of Guarantor,  enforceable against Guarantor
in accordance  with its terms,  subject to the effect of applicable  bankruptcy,
insolvency,  reorganization,  arrangement,  moratorium  or  other  similar  laws
affecting the rights of creditors generally.  Neither the execution and delivery
of this Guaranty nor the  consummation of the transactions  contemplated  hereby
will conflict with, or (with or without notice or lapse of time, or both) result
in a termination,  breach, impairment or violation of, or give rise to a default
under (i) any provision of Guarantor's articles of incorporation or bylaws, (ii)
any material  instrument  or contract to which  Guarantor is a party or by which
Guarantor is bound,  or (iii) any  federal,  state,  local or foreign  judgment,
writ,



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decree,  order,  statute,  rule or regulation  applicable  to Guarantor,  or any
property of Guarantor.

     IN WITNESS  WHEREOF,  Guarantor has executed this Continuing Lease Guaranty
as of the date first hereinabove written.

                                   Guarantor:

                                   ICG COMMUNICATIONS, INC.,
                                   a Delaware corporation



                                   By /s/ James D. Grenfell
                                      ---------------------------
                                       James D. Grenfell

                                      Its Executive Vice President
                                          and Chief Financial Officer