<PAGE>

                                                                   Exhibit 10.21

                  MASTER AGREEMENT FOR INTERNET ACCESS SERVICES

This Master Agreement for Internet Access Services ("Agreement") between
ITC^DeltaCom Communications, Inc. ("ITC^DeltaCom") and Knology, Inc.
("Customer") includes the attached Schedule 1 together with any additional
Schedules mutually agreed to in writing in the future (collectively,
"Schedules").

1. Services. ITC^DeltaCom agrees to provide Customer with Internet access
services ("Services"). Schedule 1, attached hereto and incorporated herein by
reference, contains the locations, delivery type and bandwidth of the Services
and any additional technical and operational detail required for the
implementation of the Services and is hereby agreed to and accepted by Customer.
Additional Schedules attached hereto from time to time may include any
additional locations and bandwidths requested by Customer.

2. Prices. Prices are stated in Schedule 1 and are guaranteed for the term
stated in Schedule 1 ("Term").The Term shall commence upon the Customer's first
use of the Services pursuant to this Agreement. ITC^DeltaCom shall charge
customer a monthly fee ("Monthly Fee") for the Services, as listed in the
Schedules. ITC^DeltaCom shall give Customer at least ninety (90) days notice of
a price change. In addition, Customer is responsible for applicable taxes,
tariffs, telecommunications surcharges or other governmental charges due on
account of the Services.

3. Payment. Unless otherwise stated in a Schedule, ITC^DeltaCom will invoice
Customer monthly. Customer agrees to pay within 30 days from receipt of invoice.
For overdue invoices, Customer will pay interest of 1.5% for each month or part
of a month (or the maximum allowed by law, whichever is less).

4. ITC^DeltaCom Responsibilities. ITC^DeltaCom is responsible for providing the
Services by qualified personnel in a professional manner. Except as otherwise
stated in Section 15, ITC^DELTACOM DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED,
INCLUDING THE WARRANTIES OF MERCHANTABILITY.

5. Customer Responsibilities. Customer is responsible for the manner in which
Customer uses the Services, including the maintenance and security of Customer's
data, computer network and other facilities; Customer's choice of equipment,
software and online content; and all other matters reasonably related to how
Customer uses the Services.

6. Indemnification. ITC^DeltaCom will indemnify Customer for damages, costs and
attorneys' fees Customer incurs from any claim that the Services infringes any
U.S. patent, copyright, trademark, trade secret or other intellectual property
right. Customer will indemnify ITC^DeltaCom for damages, costs and attorneys'
fees ITC^DeltaCom incurs from any claim arising from Customer's manner of using
of the Services, Customer's combination of the Services with other products or
services not provided by ITC^DeltaCom, or Customer's modification of the
Services. The indemnifying party shall conduct the defense and shall have
control of the litigation; the other party shall give prompt notice of claims
and shall cooperate in defending against the claim. THE PARTIES DISCLAIM THE
IMPLIED WARRANTY OF NON-INFRINGEMENT, RELYING INSTEAD ON THE TERMS OF THIS
SECTION.

7. IP Addresses. Customer shall be allotted a number of IP addresses which shall
correspond with Customer's estimated need for said addresses.

8. Acknowledgment. Customer agrees that ITC^DeltaCom may include Customer's name
in listings of ITC^DeltaCom's customers.


                           ITC^DeltaCom Confidential                           1

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9. Compliance with Laws. Customer shall not use or permit Customer's end users
to use the Services in ways that violate laws or ITC^DeltaCom's Acceptable Use
Policy (as it now exists or as it may be modified from time to time) which is
published on ITC^DeltaCom's web site at
http://www.itcdeltacom.com/use_policy.html, infringe the rights of others, or
interfere with users of ITC^DeltaCom's network or other networks. For example,
Customer shall not (nor shall it permit others using the Service) distribute
chain letters or unsolicited bulk electronic mail ("slamming"); propagate
computer worms or viruses; use a false identity; attempt to gain unauthorized
entry to any site or network; distribute child pornography, obscenity or
defamatory material over the Internet; or infringe copyrights, trademarks or
other intellectual property rights. Customer further agrees to comply with U.S.
export laws concerning the transmission of technical data and other regulated
materials via the Services.

      .     10. Termination. Either party may terminate or cancel this Agreement
            if the other fails to cure a material breach of the Agreement within
            thirty (30) days after receiving written notice of the breach.
            ITC^DeltaCom reserves the right, but assumes no obligation, to
            suspend performance immediately if Customer is more than thirty (30)
            days overdue in payments. If in ITC^DeltaCom's reasonable judgment,
            Customer violates Section 9 above, ITC^DeltaCom reserves the right
            to suspend or terminate the Services immediately with or without
            notice to Customer. If either party experiences a
            Bankruptcy/Insolvency Event, the Party not experiencing a
            Bankruptcy/Insolvency Event may terminate the agreement by notifying
            the other party in writing. A "Bankruptcy/Insolvency Event" is when
            a Party is unable to pay its debts when due, or any of the following
            happens to a Party under any law for the protection of debtors: The
            Party is determined to be a bankrupt or insolvent or the process to
            make this determination has been started;

      .     The Party has a receiver, administrator or liquidator appointed on
            its behalf;

      .     The Party makes an arrangement or composition with, or an assignment
            for the benefit of; its creditors;

      .     The Party goes into either voluntary (other than for reconstruction
            or amalgamation) or compulsory liquidation.

11. Early Termination Charges. If Lessee cancels any Services during the Term of
this Agreement, an early termination liability equal to the full amount of all
Monthly Fees for all months remaining in the Term shall be immediately due,
owing and payable without demand by Lessee.

12. Limitation of Liability. EXCEPT FOR INDEMNIFICATIONS PURSUANT TO SECTION 6,
NEITHER PARTY (NOR ITS SUPPLIERS OR CUSTOMERS) SHALL BE LIABLE TO THE OTHER
PARTY FOR PUNITIVE, SPECIAL, CONSEQUENTIAL, INCIDENTAL OR INDIRECT DAMAGES
INCLUDING WITHOUT LIMITATION, LOST PROFITS OR LOSS OR DAMAGE TO DATA ARISING OUT
OF THE USE OF THE SERVICES, EVEN IF THE PARTY HAS BEEN ADVISED OF THE
POSSIBILITY OF SUCH DAMAGES.

13. Limitation of Damages. EITHER PARTY'S AGGREGATE LIABILITY TO THE OTHER PARTY
RELATING TO OR ARISING OUT OF THIS AGREEMENT, WHETHER IN CONTRACT, TORT OR
OTHERWISE, SHALL NOT EXCEED (A) THE TOTAL AMOUNTS PAID OR PAYABLE BY CUSTOMER TO
ITC^DELTACOM FOR THE SERVICE IN QUESTION, DURING THE ONE-YEAR PERIOD IMMEDIATELY
PRECEDING THE EVENT WHICH GAVE RISE TO CUSTOMER'S CLAIM OR (B) $100,000.00,
WHICHEVER IS LESS.

14. Miscellaneous. The terms and conditions of this Agreement supersede all
previous agreements, proposals or representations related to the Services.
Customer may not assign this Agreement without the prior written consent of
ITC^DeltaCom. This Agreement shall be governed


                           ITC^DeltaCom Confidential                           2

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by the substantive laws of the state of Georgia. Any changes to this Agreement,
or any additional or different terms in any purchase order, acknowledgment or
other document, will not be effective unless expressly agreed to in writing by
ITC^DeltaCom and Customer.

15. Service Level.

ITC^DeltaCom's Availability Guarantee is to have the ITC^DeltaCom network
available 99.99% of the time and, as set forth below, ITC^DeltaCom will credit
Customer's account if ITC^DeltaCom fails to meet this Availability Guarantee
during any given calendar month. At Customer's request, ITC^DeltaCom will
calculate Customer's "Network Unavailability" in a calendar month. "Network
Unavailability" consists of the number of minutes that the ITC^DeltaCom network
or an ITC^DeltaCom-ordered telephone company circuit in the contiguous U.S. was
not available to Customer, but will not include unavailability continuing for an
hour or less which Customer fails to report to ITC^DeltaCom within five days, or
any unavailability resulting from (i) ITC ^DeltaCom Network maintenance, (ii)
any Customer-ordered telephone company circuits, (iii) Customer's applications,
equipment, or facilities, (iv) acts or omissions of Customer, or any use or user
of the service authorized by Customer or (v) reasons of Force Majeure . For each
cumulative hour of Network Unavailability or fraction thereof in any calendar
month, Customer's account shall be credited for the pro-rated charges for one
day of the ITC^DeltaCom Monthly Fee for the Services with respect to which this
Availability Guarantee has not been met.

      (b) ITC^DeltaCom's Latency Guarantee is average round-trip transmissions
of 85 milliseconds or less between ITC^DeltaCom-designated regional transit
backbone routers ("Hub Routers"). Latency shall be measured by averaging sample
measurements taken during a calendar month between Hub Routers If ITC^DeltaCom
fails to meet the Latency Guarantee in two consecutive calendar months,
Customer's account shall be credited for that second month and any consecutive
month in which the Latency Guarantee is not met for the pro-rated charges for
one day of the ITC^DeltaCom Monthly Fee for the service with respect to which
this Latency Guarantee has not been met. No credits will be made if failure to
meet the Latency Guarantee is attributable to reasons of Force Majeure.

16. Additional Provisions.

      (a) The failure of either Party to give notice of default or to enforce or
insist upon compliance with any terms or conditions of this Agreement, the
waiver of any term or condition of this Agreement, or the granting of an
extension of time for performance, shall not constitute the permanent waiver of
any term or condition of this Agreement, and this Agreement and each of its
provisions shall remain at all times in full force and effect until modified by
the Parties in writing.

      (b) This Agreement sets forth the entire understanding of the Parties and
supersedes any and all prior agreements, arrangements or understandings relating
to the subject matter hereof. No subsequent agreement between Customer and
ITC^DeltaCom concerning the Services shall be effective or binding unless it is
made in writing, and no representation, promise, inducement or statement or
intention has been made by either Party which is not embodied herein.

      (c) This Agreement shall be binding upon and inure to the benefit of the
Parties hereto and their respective successors or assigns; provided, however,
neither Party may assign or transfer its right or obligations under this
Agreement without prior written consent of the other Party, which consent shall
not be unreasonably withheld. Notwithstanding the foregoing, the Parties may
assign this Agreement or any of their rights and benefits hereunder without the
consent of the other Party under the following conditions: (a) to any Affiliate,
as defined below, of such Party, to the surviving Entity, as defined below, into
which such Party may merge or


                           ITC^DeltaCom Confidential                           3

<PAGE>

consolidate; or (b) to any Entity to which the Party transfers all, or
substantially all, of its business and assets, provided that the assignor shall
remain liable for all of its obligations hereunder and such assignee shall in
writing assume all obligations of the assignor hereunder arising after the
effective date of such assignment. Any prohibited assignment or delegation shall
be null and void. "Affiliate" shall be defined as any individual, corporation,
partnership, limited liability company, limited liability partnership, practice,
association, joint stock company, trust, unincorporated organization or other
venture or business vehicle (each an "Entity") in which a Party owns a fifty
percent (50%) or greater equity interest, or which is owned by a fifty percent
(50%) or greater equity interest by another party.

      (d) Notices under this Agreement shall be in writing and delivered by
overnight express courier service or by registered or certified mail, return
receipt requested, postage paid, to the person whose names and business
addresses appear herein, or as otherwise provided by proper notice hereunder,
and the effective date of any notice under this Agreement shall be the date of
delivery or refusal of such notice, and not the date of mailing.


                           ITC^DeltaCom Confidential                           4

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TO:                   ITC^DeltaCom Communications, Inc.
                      Vice President, Carrier Services
                      1791 O. G. Skinner Drive
                      West Point, GA 31833

COPY TO:              Assistant General Counsel
                      ITC^DeltaCom Communications, Inc.
                      4092 South Memorial Parkway
                      Huntsville, AL 35802

TO CUSTOMER:          Knology, Inc.
                      Attn: General Counsel
                      1241 O.G. Skinner Drive
                      West Point, Georgia 31833

      (e) If any provision of this Agreement shall be held to be invalid,
illegal or unenforceable, the validity, legality and enforceability of the
remaining provisions shall not in any way be affected or impaired thereby, and
such provision shall be deemed to be restated to reflect the Parties' original
intentions as nearly as possible in accordance with applicable law(s).

      (f) The Parties agree that in the event a decision or rating by any
governmental or quasi-governmental authority at the federal, state or local
level materially affects the rights or obligations of either Party arising out
of this Agreement, the Parties will negotiate in good faith to modify this
Agreement in light of such decision. Should said decision or ruling prevent the
continuance of these services then either Party may terminate this Agreement
with notice to the other Party without further liability hereunder, except as
may be provided in this Agreement.

      (g) This Agreement and all other documents and writings associated
herewith shall be governed by the laws of the State of Georgia, except that no
doctrine of choice of laws shall be used to apply any law other than that of
Georgia. If any part of any provision of this Agreement or any other agreement,
document or writing given pursuant to or in connection with this Agreement shall
be invalid or unenforceable under applicable law, said part shall be ineffective
to the extent of such invalidity only, without in any way affecting the
remaining parts of said provision or remaining provisions of this Agreement and
the Parties hereby agree to negotiate with respect to any such invalid or
unenforceable part to the extent necessary to render such part valid and
enforceable.

      (h) The Parties are independent contractors, and this Agreement will not
be construed as constituting either Party as partner, joint venturer or
fiduciary of the other or to create any other form of legal association that
would impose liability on one Party for the act or failure to act of the other
or as providing either Party with the right, power or authority (express or
implied) to create any duty or obligation of the other. Except as otherwise
expressly provided in this Agreement, each Party has the sole right and
obligation to supervise, manage, contract, direct, procure, perform or cause to
be performed all work to be performed by it pursuant to this Agreement.

      (i) This Agreement may be executed in counterparts. Each such counterpart
will be an original and together will constitute but one and the same document.

      (j) The Parties do not intend, nor will any section hereof be interpreted
to create, for any third party beneficiary rights with respect to either of the
Parties.


                           ITC^DeltaCom Confidential                           5

<PAGE>

      (k) The Parties agree that in any instance where consent, approval or
agreement is required of a Party in order for the other Party to perform under
or comply with the terms and conditions of this Agreement, then such Party will
not unreasonably withhold or delay such consent, approval or agreement and where
consent, approval or agreement cannot be provided, the Party will notify the
other Party in a timely manner.

      IN WITNESS WHEREOF, the Parties have caused this Agreement to be signed
and delivered on their behalf on the dates indicated below.


ITC^DELTACOM:                            CUSTOMER:

ITC^DELTACOM COMMUNICATIONS, INC.        KNOLOGY, INC.

By: ________________________________     By: ___________________________________
(Signature of Authorized                 (Signature of Authorized
Representative)                          Representative)

Name: ______________________________     Name: _________________________________
         (Print)                                 (Print)

Title: _____________________________     Title: ________________________________


Date: ______________________________     Date: _________________________________


                           ITC^DeltaCom Confidential                           6

<PAGE>

                                   SCHEDULE 1

<TABLE>
<CAPTION>
        S/POP sites, Service Requested, Existing or New Co-lo Type of Service, Physical Interface
----------------------------------------------------------------------------------------------------------------
                 Requested                                                                          Physical
   City        (No or Speed)    Existing or New    Fixed or Variable     Access Type  Co-lo (Y/N)   Interface
----------------------------------------------------------------------------------------------------------------
<S>                <C>              <C>                  <C>                 <C>           <C>        <C>
  Dallas
----------------------------------------------------------------------------------------------------------------
Birmingham
----------------------------------------------------------------------------------------------------------------
 Atlanta           1000             Existing             Fixed               PtoP          Y          GigE
----------------------------------------------------------------------------------------------------------------
 Columbia
----------------------------------------------------------------------------------------------------------------
 Gulfport
----------------------------------------------------------------------------------------------------------------
 Orlando
----------------------------------------------------------------------------------------------------------------
</TABLE>

Options for access type: ATM, Frame Relay (FR), Ethernet, Point to Point (PtoP),
Packet over Sonet (POS)

Options for physical interface: 10Mbps, 100Mbps, or 1Gbps Ethernet, DS-3, OC-3,
OC-12.

      Term:     ___X__ 12 Months  _______ 24 Months  ____ 36 Months

      Total Possible Bandwidth Requested                             1000   Mbps
                                                                   -------

      Cost per Mbps                                                $ XXX.XX
                                                                   --------

      Total Variable Bandwidth Requested                           _________Mbps
      (based on maximum speed of physical interface)
      Cost per Mbps                                                $ _______

      Total Fixed Bandwidth Requested                                 115   Mbps
                                                                   --------
      Total Monthly Recurring Cost                                 $ XX,XXX.00
                                                                   -----------
      Total Cost                                                   $ XX,XXX.00
                                                                   -----------
      Minimum Commitment                                              115   Mbps
                                                                   --------

                                 IP Information
--------------------------------------------------------------------------------
    City       IP Block(s)     Subnet info   Interface IP    Contact Name and #
--------------------------------------------------------------------------------

--------------------------------------------------------------------------------

--------------------------------------------------------------------------------

--------------------------------------------------------------------------------

                                  IP info cont.
--------------------------------------------------------------------------------
      City               BGP Peering Y/N                    AS Number
--------------------------------------------------------------------------------

--------------------------------------------------------------------------------

--------------------------------------------------------------------------------

--------------------------------------------------------------------------------


                           ITC^DeltaCom Confidential                           7

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                               Customer Equipment

<TABLE>
<CAPTION>
                      (required if Co-lo, requested for all service to aid in customer connections issues)
------------------------------------------------------------------------------------------------------------------------------------
 Rack #        Equipment      Vendor/Manufacturer & Contract #    Model #    Description & Software Generic    Slot #       Card #
------------------------------------------------------------------------------------------------------------------------------------
<S>            <C>            <C>                                 <C>        <C>                               <C>          <C>

------------------------------------------------------------------------------------------------------------------------------------

------------------------------------------------------------------------------------------------------------------------------------

------------------------------------------------------------------------------------------------------------------------------------

------------------------------------------------------------------------------------------------------------------------------------
</TABLE>

      [_]  UPGRADE OR RENEWAL TO REPLACE EXISTING INTERNET SERVICE

I.    AFTER HOURS TECHNICAL CONTACT INFORMATION:
      Name: Knology NOC      Cellular: 706-773-0148    Phone: 800-453-1777
      Fax:                   Email:                    Pager:

II.   GENERAL INFORMATION:

      A.    Customer Estimated Installation Date for Circuit:

      B.    Estimated Installation Date for Internet Connectivity: Existing

      C.    Is the client an existing Internet Customer? [_] Yes or [_] No

SKIP VI. DUE TO NO EQUIPMENT BEING INSTALLED BY ITC^DELTACOM

VI.   INSTALLATION INFORMATION:

      A.    Installation instructions. Include special instructions, such as,
            Firewall, IP-IPX, NAT and any equipment beyond the router. BE
            SPECIFIC! (Use comment section if necessary).



      B.    Are there ample network interfaces for equipment being installed?
            [_] Yes or [_] No

      C.    Are the network ports located less than 20 feet from the
            (t1/56/64/ISDN) jack location? [_] Yes or [_] No

      D.    What type of File Servers is on location? [_] Unix [_] Novell
            [_] Windows NT

      E.    What type of Operating System is being used? [_] WINTEL-WINNT
            [_] UNIX/LINUX [_] MAC/OS Other:



VII.  NETWORK INFORMATION:

      A.    Network Type:


                           ITC^DeltaCom Confidential                           8

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            1.    Ethernet: [_] 10baseT [_] 100baseTX [_] Other:

            2.    Token Ring: [_] 4 Megabits [_] 16 Megabits [_] RJ45 Wiring [_]
                  IBM Wiring

      B.    What network protocols are currently being used?

            1.    [_] TCP/IP

                  a.    What range of IP addresses is currently being used?
                           .   .   .    -    .   .   .

                  b.    Network Numbers to be used were: [_] Assigned by another
                        ISP [_] Self Generated [_] Assigned by Internic

                  c.    Would the customer like to use Network Address
                        Translation (NAT)? [_] Yes or [_] no

                  d.    Is it possible for the customer to renumber the network?
                        [_] Yes or [_] No

                  e.    Would the customer like for all computers to be able to
                        access the Internet? [_] Yes or [_] No

            2.    [_] IPX

            3.    [_] SNA

            4.    [_] NetBeui

      C.    What type of network security would the customer plan to install:
            [_] Firewall [_] Router Filters [_] None

      D.    How many IP addresses will be needed?

      E.    If the customer will have his or her own SMTP/POP mail server or Web
            server, complete the following:

<TABLE>
<CAPTION>
------------------------------------------------------------------------------------------------------------------------------------
Type (ex. Sendmail Exchange Server)     Domain Included      IP Addresses           Fully Qualified Name of     Web or SMTP/POP
                                                                                    Server
------------------------------------------------------------------------------------------------------------------------------------
<S>                                     <C>                  <C>                    <C>                         <C>
                                                                                                                [_] Web [_] SMTP/POP
------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                [_] Web [_] SMTP/POP
------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                [_] Web [_] SMTP/POP
------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                [_] Web [_] SMTP/POP
------------------------------------------------------------------------------------------------------------------------------------
</TABLE>

      F.    Will or is ITC^DeltaCom hosting the DNS for the Customer? [_] Yes or
            [_] No

      G.    Domain Registration Form Completed for: [_] Domain Registration or
            [_] Transfer


                           ITC^DeltaCom Confidential                           9

<PAGE>

X. COMMENTS:



ITC/\DELTACOM:                           CUSTOMER:

ITC/\DELTACOM COMMUNICATIONS, INC.       KNOLOGY INC.

By: ________________________________     By: ___________________________________
(Signature of Authorized                 (Signature of Authorized
Representative)                          Representative)

Name: ______________________________     Name: _________________________________
         (Print)                                  (Print)

Title: _____________________________     Title: ________________________________


Date: ______________________________     Date: _________________________________


                           ITC/\DeltaCom Confidential                         10