Document:

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                                                                     EXHIBIT 4.1

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                               AT&T BROADBAND, LLC

                                       and

                          THE BANK OF NEW YORK, Trustee

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

                         SEVENTH SUPPLEMENTAL INDENTURE
                           Dated as of March 21, 2000

              Supplement to Indenture Dated as of January 29, 1996
                               as supplemented by
           First Supplemental Indenture Dated as of January 29, 1996,
             Second Supplemental Indenture Dated as of May 22, 1996,
            Third Supplemental Indenture Dated as of March 14, 1997,
            Fourth Supplemental Indenture Dated as of March 24, 1997,
           Fifth Supplemental Indenture Dated as of March 9, 1999, and
              Sixth Supplemental Indenture Dated February 25, 2000

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

              8.72% Subordinated Deferrable Interest Notes due 2045
             10.00% Subordinated Deferrable Interest Notes due 2045
              9.72% Subordinated Deferrable Interest Notes due 2036

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         SEVENTH SUPPLEMENTAL INDENTURE, dated as of March 21, 2000 (this
"Supplemental Indenture"), among AT&T Broadband, LLC, a Delaware limited
liability company (the "Company"), AT&T Corp., a New York corporation (the
"Guarantor"), and The Bank of New York, a New York banking corporation, as
trustee (the "Trustee").

         WHEREAS the Company is the successor issuer under the Indenture, dated
as of January 29, 1996, as supplemented by a First Supplemental Indenture, dated
as of January 29, 1996, a Second Supplemental Indenture, dated as of May 22,
1996, a Third Supplemental Indenture, dated as of March 14, 1997, a Fourth
Supplemental Indenture, dated as of March 24, 1997, a Fifth Supplemental
Indenture, dated as of March 9, 1999, and a Sixth Supplemental Indenture, dated
as of February 25, 2000 (collectively, the "Original Indenture", and together
with this Supplemental Indenture, the "Indenture"), pursuant to which the
Company (as successor issuer) issued, and the Trustee authenticated and
delivered the following securities, among others, which are, as of the date
hereof, outstanding:

(a) $515,463,925 aggregate principal amount of the Company's 8.72% Subordinated
Deferrable Interest Notes due 2045 (the "Trust I Notes");

(b) $515,463,925 aggregate principal amount of the Company's 10.00% Subordinated
Deferrable Interest Notes due 2045 (the "Trust II Notes"); and

(c) $206,185,575 aggregate principal amount of the Company's 9.72% Subordinated
Deferrable Interest Notes due 2036 (the "Trust IV Notes", and together with the
Trust I Notes and the Trust II Notes, the "Subject Securities");

         WHEREAS TCI Communications Financing I, a Delaware statutory business
trust ("Trust I"), has issued $500,000,000 aggregate liquidation amount of its
8.72% Trust Originated Preferred Securities, representing undivided beneficial
interests in the assets of Trust I, and has invested the proceeds from such
issuance in the Trust I Notes;

         WHEREAS TCI Communications Financing II, a Delaware statutory business
trust ("Trust II"), has issued $500,000,000 aggregate liquidation amount of its
10.00% Trust Preferred Securities, representing undivided beneficial interests
in the assets of Trust II, and has invested the proceeds from such issuance in
the Trust II Notes;

         WHEREAS TCI Communications Financing IV, a Delaware statutory business
trust ("Trust IV"), has issued $200,000,000 aggregate liquidation amount of its
9.72% Trust Preferred Securities, representing undivided beneficial interests in
the assets of Trust IV, and has invested the proceeds from such issuance in the
Trust IV Notes;

         WHEREAS the Company is the obligor with respect to the Subject
Securities;

         WHEREAS the Guarantor desires to irrevocably and unconditionally
guarantee, on a subordinated basis, the full and punctual payment of principal
of and interest on the Subject

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Securities when due, whether at maturity, by acceleration, by redemption or
otherwise, and all other monetary obligations of the Company under the Subject
Securities and, with respect to the Subject Securities, under the Indenture
(including obligations of the Company to the Trustee), and the full and punctual
performance (within applicable grace periods) of all other obligations of the
Company under the Subject Securities and, with respect to the Subject
Securities, under the Indenture;

         WHEREAS the Company and the Guarantor have requested that the Trustee
execute and deliver this Supplemental Indenture and all requirements necessary
to make this Supplemental Indenture a valid instrument in accordance with its
terms and to make the guarantee provided for herein the valid obligation of the
Guarantor, and the execution and delivery of this Supplemental Indenture have
been duly authorized in all respects.

         NOW THEREFORE, in consideration of the mutual promises contained herein
and for other good and valuable consideration, the receipt and sufficiency of
which is hereby acknowledged the Company, the Guarantor and the Trustee hereby
agree as follows for the equal and ratable benefit of the Holders of the Subject
Securities:

         SECTION 1. Definitions.

         (a) Capitalized terms used herein but not defined herein have the
meanings ascribed to such terms in the Original Indenture.

         (b) Article I, Section 1.01, of the Original Indenture is hereby
supplemented, solely with respect to this Supplemental Indenture, to add the
following definitions:

                   "Guarantor Senior Indebtedness" means all indebtedness,
         obligations or liabilities of the Guarantor, whether outstanding at the
         date of effectiveness of the Seventh Supplemental Indenture to the
         Indenture or thereafter incurred, assumed, guaranteed or otherwise
         created (including, without limitation, interest accruing on or after a
         bankruptcy or other similar event, whether or not an allowed claim
         therein), in respect of (A) indebtedness of the Guarantor for money
         borrowed, (B) indebtedness evidenced by securities, debentures, bonds,
         notes or other similar instruments issued by the Guarantor, (C) all
         capital lease obligations of the Guarantor, (D) all obligations of the
         Guarantor issued or assumed as the deferred purchase price of property,
         all conditional sale obligations of the Guarantor and all obligations
         of such obligor under any title retention agreement (but excluding
         trade accounts payable arising in the ordinary course of business), (E)
         all obligations of the Guarantor for reimbursement on any letter of
         credit, banker's acceptance, security purchase facility or similar
         credit transaction, (F) all obligations of the type referred to in
         clauses (A) through (E) of other Persons for the payment of which the
         Guarantor is responsible or liable as obligor, guarantor or otherwise,
         and (G) all obligations of the type referred to in clauses (A) through
         (F) of other Persons secured by any lien on any property or asset of
         the Guarantor (whether or not such obligation is assumed by such
         obligor), except for any such indebtedness, obligations or liabilities
         the terms of which expressly provide that

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         such indebtedness, obligation or liability is equal or subordinated in
         right of payment to the Guarantor's guarantee with respect to the
         Subject Securities, as the case may be. For greater certainty,
         "Guarantor Senior Indebtedness" includes all indebtedness, obligations
         or liabilities between or among the Guarantor and its Affiliates,
         except for such indebtedness, obligations or liabilities the terms of
         which expressly provide that such indebtedness, obligation or liability
         is equal or subordinated in right of payment to the Guarantor's
         guarantee with respect to the Subject Securities, as the case may be.

                  "Guarantor Senior Indebtedness Representative" means any
         Person whom the Guarantor has, by written notice to the Trustee,
         identified as the indenture trustee or other trustee, agent or
         representative for an issue of Guarantor Senior Indebtedness.

         SECTION 2. Guarantee.

         (a) The Guarantor irrevocably and unconditionally guarantees, on a
subordinated basis as set forth herein (the "Guarantee"), to each Holder of
Subject Securities and to the Trustee and its successors and assigns, (i) the
full and punctual payment of principal of and interest on the Subject Securities
when due, whether at maturity, by acceleration, by redemption or otherwise, and
all other monetary obligations of the Company with respect to the Subject
Securities under the Indenture (including obligations of the Company to the
Trustee) and the Subject Securities and (ii) the full and punctual performance
(within applicable grace periods) of all other obligations of the Company with
respect to the Subject Securities under the Indenture and the Subject
Securities.

         (b) The Guarantor further agrees that the Guarantee constitutes a
guarantee of payment and performance and not of collection.

         (c) The obligations of the Guarantor to make any payment hereunder may
be satisfied by causing the Company to make such payment.

         (d) The Guarantor also agrees to pay any and all costs and expenses
(including reasonable attorneys' fees) incurred by the Trustee or any Holder of
Subject Securities in enforcing any of their respective rights under the
Guarantee.

         SECTION 3. Subordination.

         The Guarantee is hereby expressly subordinated in right of payment, to
the extent and in the manner provided in this Supplemental Indenture, to the
prior payment in full in cash or cash equivalents of all Guarantor Senior
Indebtedness and such subordination is for the benefit of the holders of
Guarantor Senior Indebtedness. Upon any payment or distribution of all or
substantially all the assets of the Guarantor, whether voluntary or involuntary,
or upon any reorganization, readjustment, arrangement or similar proceeding
relating to the Guarantor or its property, whether or not the Guarantor is a
party thereto and whether in bankruptcy, insolvency, receivership or similar

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proceedings, or upon any assignment by the Guarantor for the benefit of
creditors or upon any other marshaling of the assets and liabilities of the
Guarantor:

                  (i) all Guarantor Senior Indebtedness shall first be paid in
         full in cash or cash equivalents, or provisions made for such payment
         by deposit thereof in trust with a bank or banks (either theretofore
         acting as trustees under indentures pursuant to which Guarantor Senior
         Indebtedness shall have been issued or duly appointed paying agents for
         the purpose), before any payment is made in respect of the Guarantee;

                  (ii) any payment in respect of the Guarantee to which the
         Holders of Subject Securities would be entitled except for the
         provisions of this Section shall be paid or delivered by the Guarantor
         or the liquidating trustee or agent or other Person making such
         payment, whether a trustee in bankruptcy, a receiver or liquidating
         trustee or other trustee or agent, directly and ratably to the holders
         of Guarantor Senior Indebtedness or the Guarantor Senior Indebtedness
         Representatives, as the case may be (subject to any subordination of
         any class of Guarantor Senior Indebtedness, by the provisions thereof,
         to any other class or classes of Guarantor Senior Indebtedness),
         according to the aggregate amounts remaining unpaid on account of the
         principal of, and the premium, if any, and interest on, and other
         monetary obligation with respect to, the Guarantor Senior Indebtedness,
         to the extent necessary to make payment in full of all Guarantor Senior
         Indebtedness remaining unpaid, after giving effect to any concurrent
         payment or distribution, or provision therefor, to the holders of such
         Guarantor Senior Indebtedness; and

                  (iii) in the event that, notwithstanding the foregoing, any
         payment of any kind or character in respect of the Guarantee shall be
         received by the Trustee or the Holders of Subject Securities before all
         Guarantor Senior Indebtedness is paid in full, or provision made as
         aforesaid for its payment, such payment shall be held in trust for the
         ratable benefit of and shall be ratably paid over or delivered to the
         holders of Guarantor Senior Indebtedness remaining unpaid or unprovided
         for or the Guarantor Senior Indebtedness Representatives, as provided
         in the foregoing subparagraph (ii), for application to the payment of
         all principal of, and premium, if any, and interest on, and other
         monetary obligation with respect to, such Guarantor Senior Indebtedness
         remaining unpaid until all such Guarantor Senior Indebtedness shall
         have been paid in full, after giving effect to any concurrent payment
         or distribution, or provision therefor, to the holders of such
         Guarantor Senior Indebtedness.

         SECTION 4. Default on Guarantor Senior Indebtedness.

         Subject to the provisions of Section 5, in the event and during the
continuation of any default in the payment of principal of, or premium, if any,
or interest on, or other monetary obligation with respect to, any Guarantor
Senior Indebtedness beyond any applicable period of grace, or in the event that
any event of default with respect to any Guarantor Senior Indebtedness shall
have occurred and be continuing, unless and until such default or event of
default shall have been cured or waived or shall have ceased to exist, no
payment shall be made by the Guarantor in respect of the Guarantee.

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Nothing contained in this Section or elsewhere in this Supplemental Indenture
shall, however, prevent the application by the Trustee of any moneys deposited
with it hereunder by the Guarantor in respect of the Guarantee, if, at the time
of such deposit, the Trustee did not have written notice of any event
prohibiting the making of such deposit by the Guarantor.

         The Guarantor shall give prompt written notice to the Trustee of any
facts that would prohibit the making of any payment of moneys in respect of the
Guarantee, including any dissolution, winding up, liquidation or reorganization
of the Guarantor. Anything in this Section or elsewhere in this Supplemental
Indenture to the contrary notwithstanding, the Trustee shall not be charged with
knowledge of the existence of any Guarantor Senior Indebtedness or of any
default or event of default with respect to any Guarantor Senior Indebtedness or
of any other facts that would prohibit the making of any payment of moneys
hereunder, unless and until the Trustee shall have received notice in writing to
that effect signed by an officer of the Guarantor or by a holder of Guarantor
Senior Indebtedness who shall have been certified by the Guarantor or otherwise
established to the reasonable satisfaction of the Trustee to be such holder or
by a Guarantor Senior Indebtedness Representative.

         SECTION 5. Disputes with Holders of Certain Guarantor Senior
Indebtedness.

         Any failure by the Guarantor to make any payment on or perform any
other obligation under Guarantor Senior Indebtedness, other than Guarantor
Senior Indebtedness consisting of any indebtedness incurred by the Guarantor or
assumed or guaranteed, directly or indirectly, by the Guarantor for money
borrowed (or any deferral, renewal, extension or refunding thereof) or
consisting of any indebtedness or obligation in which the provisions of this
Section shall have been waived by the Guarantor in the instrument or instruments
by which the Guarantor incurred, assumed, guaranteed or otherwise created such
indebtedness or obligation, shall not be deemed a default or event of default
under Section 4 hereof for so long as (a) the Guarantor disputes its obligation
to make such payment or perform such obligation and (b) either (i) such dispute
does not result in a judgment against the Guarantor that remains undischarged,
unbonded or in force for more than the applicable appeal period or (ii) in the
event of such a judgment, the Guarantor in good faith prosecutes an appeal or
other proceeding for review and the Guarantor has obtained a stay of execution
from such judgment pending such appeal or review.

         SECTION 6. When Payment Must Be Paid Over.

         If a payment is made pursuant to the Guarantee that because of Section
4 or 5 should not have been made to the Holders of the Subject Securities, the
Holders of Subject Securities who receive the payment shall hold it in trust for
holders of Guarantor Senior Indebtedness and pay it over to them as their
interests may appear.

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         SECTION 7. Relative Rights.

         This Section defines the relative rights of Holders of Subject
Securities with respect to the Guarantee and holders of Guarantor Senior
Indebtedness. Nothing in this Indenture shall:

         (a) impair, as between the Guarantor and Holders of Subject Securities,
the obligation of the Guarantor, which is absolute and unconditional, to make
payment under the Guarantee when, as and if due pursuant to this Supplemental
Indenture;

         (b) affect the relative rights of Holders of Subject Securities and
creditors of the Guarantor other than holders of Guarantor Senior Indebtedness;
or

         (c) prevent the Trustee or any Holder of Subject Securities from
exercising its available remedies with respect to the Guarantee, subject to the
rights of holders of Guarantor Senior Indebtedness to receive distributions
otherwise payable to Holders of Subject Securities.

         SECTION 8. Subordination May Not Be Impaired by Guarantor.

         No right of any holder of Guarantor Senior Indebtedness to enforce the
subordination of the Guarantee shall be impaired by any act or failure to act by
the Guarantor or by its failure to comply with this Supplemental Indenture.

         SECTION 9. SEC Reports.

         The Guarantor shall file with the Trustee within 15 days after it files
them with the SEC copies of the annual reports and of the information, documents
and other reports (or copies of such portions of any of the foregoing as the SEC
may by rules and regulations prescribe) which the Guarantor is required to file
with the SEC pursuant to Section 13 or 15(d) of the Securities Exchange Act of
1934.

         SECTION 10. Conflict with the TIA.

         If any provision of this Supplemental Indenture modifies or excludes
any provision of the TIA that is required under such Act to be part of and
govern the Indenture, the latter provision of the TIA shall control. If any
provision hereof modifies or excludes any provision of the TIA that may be so
modified or excluded, the latter provision of the TIA shall be deemed to apply
to this Supplemental Indenture, as so modified or excluded, as the case may be.

         SECTION 11. Date and Time of Effectiveness.

         This Supplemental Indenture shall become a legally effective and
binding instrument at and as of the date hereof.

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         SECTION 12. Supplemental Indenture Incorporated Into Indenture.

         The terms and conditions of this Supplemental Indenture shall be deemed
to be part of the Indenture for all purposes relating to the Subject Securities.
The Original Indenture, is hereby incorporated by reference herein and the
Original Indenture, as supplemented by this Supplemental Indenture, is in all
respects adopted, ratified and confirmed.

         SECTION 13. Subject Securities Deemed Conformed.

         As of the date hereof, the provisions of the Subject Securities then
outstanding shall be deemed to be conformed, without the necessity for any
reissuance or exchange of such Subject Security or any other action on the part
of the Holders of Subject Securities, the Company or the Trustee, so as to
reflect this Supplemental Indenture.

         SECTION 14. Successors.

         All agreements of the Company, the Guarantor and the Trustee in this
Supplemental Indenture and in the Indenture shall bind their respective
successors.

         SECTION 15. Benefits of Supplemental Indenture.

         Nothing in this Supplemental Indenture, express or implied, shall give
to any person, other than the parties hereto and their successors hereunder and
the Holders of Subject Securities, any benefit or any legal or equitable right,
remedy or claim under this Supplemental Indenture or the Indenture.

         SECTION 16. Separability.

         In case any provision in this Supplemental Indenture, or in the
Indenture, shall be invalid, illegal or unenforceable, the validity, legality
and enforceability of the remaining provisions shall not in any way be affected
or impaired thereby, it being intended that all of the provisions hereof shall
be enforceable to the full extent permitted by law.

         SECTION 17. Headings.

         The section headings of this Supplemental Indenture have been inserted
for convenience of reference only, are not to be considered a part of this
Supplemental Indenture and shall in no way modify or restrict any of the terms
or provisions hereof.

         SECTION 18. Notices.

         All notices provided for herein shall be in writing, duly signed by the
party giving such notice, and shall be delivered, telecopied or mailed by first
class mail as follows:

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                  (a) if given to the Guarantor, to the Guarantor's mailing
address set forth below or such other address as the Guarantor may give notice
of to the Holders of the Subject Securities:

                           AT&T Corp.
                           32 Avenue of the Americas
                           New York, New York 10013-2412
                                Attention: Legal Department;

                  (b) if given to the Trustee, to the address set forth in the
Indenture or to such other address as the Trustee may give notice of to the
Holders of Subject Securities; and

                  (c) if given to any Holder of Subject Securities, at the
address set forth on the books and records of Trust I, Trust II or Trust IV, as
applicable.

         All such notices shall be deemed to have been given when received in
person, telecopied with receipt confirmed, or mailed by first class mail,
postage prepaid except that if a notice or other document is refused delivery or
cannot be delivered because of a changed address of which no notice was given,
such notice or other document shall be deemed to have been delivered on the date
of such refusal or inability to deliver.

         SECTION 19. GOVERNING LAW.

         THIS SUPPLEMENTAL INDENTURE SHALL BE GOVERNED AND CONSTRUED IN
ACCORDANCE WITH THE INTERNAL LAWS OF THE STATE OF NEW YORK.

         SECTION 20. Counterparts.

         This Supplemental Indenture may be executed in two or more
counterparts, each of which shall constitute an original, but all of which when
taken together shall constitute the same instrument.

         SECTION 21. Trustee Not Responsible for Recitals.

         The recitals herein contained are made by the Company and the
Guarantor, and not by the Trustee, and the Trustee assumes no responsibility for
the correctness thereof. The Trustee shall not be responsible in any manner
whatsoever for or in respect of the validity or sufficiency of this Supplemental
Indenture.

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         IN WITNESS WHEREOF, the parties hereto have caused this Supplemental
Indenture to be duly executed as of the date first above written.

                                  AT&T BROADBAND, LLC

                                  By:
                                      ------------------------------------------
                                  Name:
                                  Title:

                                  AT&T CORP.

                                  By:
                                      ------------------------------------------
                                  Name:
                                  Title:

                                  THE BANK OF NEW YORK, as Trustee

                                  By:
                                      ------------------------------------------
                                  Name:
                                  Title:

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                                                                     EXHIBIT 4.2

                   GUARANTEE OF PREFERRED SECURITIES GUARANTEE

         GUARANTEE OF PREFERRED SECURITIES GUARANTEE (this "Agreement"), dated
as of March 21, 2000, among AT&T Broadband, LLC, a Delaware limited liability
company (the "Original Guarantor"), AT&T Corp., a New York corporation (the
"Additional Guarantor"), and The Bank of New York, a New York banking
corporation, as trustee (the "Guarantee Trustee").

         WHEREAS in connection with the issuance by TCI Communications Financing
I, a Delaware statutory business trust (the "Trust"), of $500,000,000 aggregate
liquidation amount of its 8.72% Trust Originated Preferred Securities (the
"Preferred Securities") representing undivided beneficial interests in the
assets of the Trust, TCI Communications, Inc. ("TCIC") and the Guarantee Trustee
entered into a Preferred Securities Guarantee Agreement, dated as of January 29,
1996 (the "Original Guarantee Agreement"), pursuant to which TCIC irrevocably
and unconditionally agreed, to the extent set forth therein, to pay to the
Holders of the Preferred Securities the Guarantee Payments on the terms and
conditions set forth therein (collectively, the "Original Guarantee");

         WHEREAS the Original Guarantor has succeeded to all of TCIC's
obligations with respect to the Original Guarantee Agreement; and

         WHEREAS the Additional Guarantor proposes in and by this Agreement to
irrevocably and unconditionally guarantee, on a subordinated basis, the Original
Guarantor's obligation under the Original Guarantee Agreement to pay to the
Holders of the Preferred Securities the Guarantee Payments.

         NOW THEREFORE, in consideration of the mutual promises contained herein
and for other good and valuable consideration, the receipt and sufficiency of
which is hereby acknowledged, the Original Guarantor, the Additional Guarantor
and the Guarantee Trustee hereby agree as follows:

         SECTION 1. Capitalized Terms.

         Capitalized terms used herein and not defined herein shall have the
meanings ascribed to such terms in the Original Guarantee Agreement.

         SECTION 2. Powers and Duties of the Guarantee Trustee.

         (a) This Agreement shall be held by the Guarantee Trustee in trust for
the benefit of the Holders of the Preferred Securities, and the Guarantee
Trustee shall not transfer its right, title and interest in this Agreement to
any Person except to a Holder of Preferred Securities exercising his or her
rights pursuant to Section 7 or to a successor guarantee trustee possessing the
qualifications to act as Guarantee Trustee under this Agreement in accordance
with Section 4 (the "Successor Guarantee Trustee") on acceptance by such
Successor Guarantee Trustee of its appointment to act as Guarantee Trustee. The
right, title and interest of the Guarantee Trustee to this Agreement shall vest
automatically in any Successor Guarantee Trustee, and such vesting (and
cessation as to the

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Guarantee Trustee) of right, title and interest shall be effective whether or
not conveyancing documents have been executed and delivered pursuant to the
appointment of such Successor Guarantee Trustee.

         (b) If a default by the Additional Guarantor on any of its payments or
other obligations under this Agreement (an "Event of Default") occurs and is
continuing, the Guarantee Trustee shall enforce this Agreement for the benefit
of the Holders of Preferred Securities.

         (c) In case an Event of Default has occurred (that has not been cured
or waived pursuant to Section 12), the Guarantee Trustee shall exercise such of
the rights and powers vested in it by this Agreement, and use the same degree of
care and skill in their exercise, as a prudent person would exercise or use
under the circumstances in the conduct of his or her own affairs. No provision
of this Agreement shall be construed to relieve the Guarantee Trustee from
liability for its own negligent action, its own negligent failure to act or its
own willful misconduct, except that:

                  (i) prior to the occurrence of an Event of Default and after
         the curing or waiving of all such Events of Default that may have
         occurred:

                           (A) the duties and obligations of the Guarantee
                  Trustee under this Agreement shall be determined solely by the
                  express provisions of this Agreement, and the Guarantee
                  Trustee shall not be liable under this Agreement except for
                  the performance of such duties and obligations as are
                  specifically set forth in this Agreement, and no implied
                  covenants or obligations shall be read into this Agreement
                  against the Guarantee Trustee; and

                           (B) in the absence of bad faith on the part of the
                  Guarantee Trustee, the Guarantee Trustee may conclusively
                  rely, as to the truth of the statements and the correctness of
                  the opinions expressed therein, upon any certificates or
                  opinions furnished to the Guarantee Trustee and conforming to
                  the requirements of this Agreement; but in the case of any
                  such certificates or opinions that by any provision hereof are
                  specifically required to be furnished to the Guarantee
                  Trustee, the Guarantee Trustee shall be under a duty to
                  examine the same to determine whether or not they conform to
                  the requirements of this Agreement;

                  (ii) the Guarantee Trustee shall not be liable for any error
         of judgment made in good faith by a Responsible Officer of the
         Guarantee Trustee, unless it shall be proved that the Guarantee Trustee
         was negligent in ascertaining the pertinent facts upon which such
         judgment was made. For purposes hereof, the term "Responsible Officer"
         means, with respect to the Guarantee Trustee, any vice president, any
         assistant vice president, any assistant secretary, any assistant
         treasurer, any trust officer or assistant trust officer or any other
         officer of the corporate trust department of the Guarantee Trustee
         customarily per forming functions similar to those performed by any of
         the above designated officers and also means, with respect to a
         particular corporate trust matter, any other officer to whom such

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         matter is referred because of that officer's knowledge of and
         familiarity with the particular subject;

                  (iii) the Guarantee Trustee shall not be liable with respect
         to any action taken or omitted to be taken by it pursuant to this
         Agreement in good faith in accordance with the direction of the Holders
         of not less than a Majority in liquidation amount of the Securities
         relating to the time, method and place of conducting any proceeding for
         any remedy available to the Guarantee Trustee, or exercising any trust
         or power conferred upon the Guarantee Trustee under this Agreement; and

                  (iv) no provision of this Agreement shall require the
         Guarantee Trustee to expend or risk its own funds or otherwise incur
         personal financial liability in the performance of any of its duties or
         in the exercise of any of its rights or powers, if the Guarantee
         Trustee shall have reasonable grounds for believing that the repayment
         of such funds or liability is not reasonably assured to it under the
         terms of this Agreement or adequate indemnity against such risk or
         liability is not reasonably assured to it.

         (d) This Agreement and all moneys received by the Guarantee Trustee
hereunder in respect of the Guarantee Payments will not be subject to any right,
charge, security interest, lien or claim of any kind in favor of, or for the
benefit of, the Guarantee Trustee or its agents or their creditors.

         SECTION 3. Certain Rights of the Guarantee Trustee.

         (a) Subject to the provisions of Section 2:

                  (i) The Guarantee Trustee may rely, and shall be fully
         protected in acting or refraining from acting upon, any resolution,
         certificate, statement, instrument, opinion, report, notice, request,
         direction, consent, order, bond, debenture, note, other evidence of
         indebtedness or other paper or document believed by it to be genuine
         and to have been signed, sent or presented by the proper party or
         parties. The Guarantee Trustee shall not be bound to make any
         investigation into the facts or matters stated in any resolution,
         certificate, statement, instrument, opinion, report, notice, request,
         direction, consent, order, bond, debenture, note, other evidence of
         indebtedness or other paper or document, but the Guarantee Trustee, in
         its discretion, may make such further inquiry or investigation into
         such facts or matters as it may see fit.

                  (ii) Any direction or act of the Additional Guarantor
         contemplated by this Agreement shall be sufficiently evidenced by an
         Officers' Certificate of the Additional Guarantor.

                  (iii) Whenever, in the administration of this Agreement, the
         Guarantee Trustee shall deem it desirable that a matter be proved or
         established before taking, suffering or omitting any action hereunder,
         the Guarantee Trustee (unless other evidence is herein specifically

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         prescribed) may, in the absence of bad faith on its part, request and
         rely upon an Officers' Certificate which, upon receipt of such
         request, shall be promptly delivered by the Additional Guarantor.

                  (iv) The Guarantee Trustee shall have no duty to see to any
         recording, filing or registration of any instrument (or any
         rerecording, refiling or reregistration thereof).

                  (v) The Guarantee Trustee may consult with counsel of its
         selection, and the advice or opinion of such counsel with respect to
         legal matters shall be full and complete authorization and protection
         in respect of any action taken, suffered or omitted by it hereunder in
         good faith and in accordance with such advice or opinion. Such counsel
         may be counsel to the Additional Guarantor or any of its Affiliates and
         may include any of its employees. The Guarantee Trustee shall have the
         right at any time to seek instructions concerning the administration of
         this Agreement from any court of competent jurisdiction.

                  (vi) The Guarantee Trustee shall be under no obligation to
         exercise any of the rights or powers vested in it by this Agreement at
         the request or direction of any Holder, unless such Holder shall have
         provided to the Guarantee Trustee such adequate security and indemnity
         as would satisfy a reasonable person in the position of the Guarantee
         Trustee, against the costs, expenses (including attorneys' fees and
         expenses) and liabilities that might be incurred by it in complying
         with such request or direction, including such reasonable advances as
         may be requested by the Guarantee Trustee; provided that, nothing
         contained in this clause (vi) shall be taken to relieve the Guarantee
         Trustee, upon the occurrence of an Event of Default, of its obligation
         to exercise the rights and powers vested in it by this Agreement.

                  (vii) The Guarantee Trustee may execute any of the trusts or
         powers hereunder or per form any duties hereunder either directly or by
         or through agents or attorneys, and the Guarantee Trustee shall not be
         responsible for any misconduct or negligence on the part of any agent
         or attorney appointed with due care by it hereunder.

                  (viii) Any action taken by the Guarantee Trustee or its agents
         hereunder shall bind the Holders of the Preferred Securities, and the
         signature of the Guarantee Trustee or its agents alone shall be
         sufficient and effective to perform any such action. No third party
         shall be required to inquire as to the authority of the Guarantee
         Trustee to so act or as to its compliance with any of the terms and
         provisions of this Agreement, both of which shall be conclusively
         evidenced by the Guarantee Trustee's or its agent's taking such action.

                  (ix) Whenever in the administration of this Agreement the
         Guarantee Trustee shall deem it desirable to receive instructions with
         respect to enforcing any remedy or right or taking any other action
         hereunder, the Guarantee Trustee (i) may request instructions from the
         Holders of a Majority in liquidation amount of the Securities, (ii) may
         refrain from

                                       4
<PAGE>   5

         enforcing such remedy or right or taking such other action until such
         instructions are received, and (iii) shall be protected in acting in
         accordance with such instructions.

         (b) No provision of this Agreement shall be deemed to impose any duty
or obligation on the Guarantee Trustee to perform any act or acts or exercise
any right, power, duty or obligation conferred or imposed on it in any
jurisdiction in which it shall be illegal, or in which the Guarantee Trustee
shall be unqualified or incompetent in accordance with applicable law, to
perform any such act or acts or to exercise any such right, power, duty or
obligation. No permissive power or authority available to the Guarantee Trustee
shall be construed to be a duty.

         SECTION 4. Guarantee Trustee; Eligibility

         (a) There shall at all times be a Guarantee Trustee which shall:

                  (i) not be an Affiliate of the Additional Guarantor; and

                  (ii) be a corporation organized and doing business under the
         laws of the United States of America or any State or Territory thereof
         or of the District of Columbia, or a corporation or Person permitted by
         the Securities and Exchange Commission to act as an institutional
         trustee under the Trust Indenture Act, authorized under such laws to
         exercise corporate trust powers, having a combined capital and surplus
         of at least 50 million U.S. dollars ($50,000,000), and subject to
         supervision or examination by Federal, State, Territorial or District
         of Columbia authority. If such corporation publishes reports of
         condition at least annually, pursuant to law or to the requirements of
         the supervising or examining authority referred to above, then, for the
         purposes of this clause (ii), the combined capital and surplus of such
         corporation shall be deemed to be its combined capital and surplus as
         set forth in its most recent report of condition so published.

         (b) If at any time the Guarantee Trustee shall cease to be eligible to
so act under Section 4(a), the Guarantee Trustee shall immediately resign in the
manner and with the effect set out in Section 5(c).

         (c) If the Guarantee Trustee has or shall acquire any "conflicting
interest" within the meaning of Section 310(b) of the Trust Indenture Act, the
Guarantee Trustee and Additional Guarantor shall in all respects comply with the
provisions of Section 310(b) of the Trust Indenture Act.

         SECTION 5. Appointment, Removal and Resignation of Guarantee Trustees

         (a) Subject to Section 5(b), the Guarantee Trustee may be appointed or
removed without cause at any time by the Additional Guarantor.

                                       5
<PAGE>   6

         (b) The Guarantee Trustee shall not be removed in accordance with
Section 5(a) until a Successor Guarantee Trustee has been appointed and has
accepted such appointment by written instrument executed by such Successor
Guarantee Trustee and delivered to the Additional Guarantor.

         (c) The Guarantee Trustee appointed to office shall hold office until a
Successor Guarantee Trustee shall have been appointed or until its removal or
resignation. The Guarantee Trustee may resign from office (without need for
prior or subsequent accounting) by an instrument in writing executed by the
Guarantee Trustee and delivered to the Additional Guarantor, which resignation
shall not take effect until a Successor Guarantee Trustee has been appointed and
has accepted such appointment by instrument in writing executed by such
Successor Guarantee Trustee and delivered to the Additional Guarantor and the
resigning Guarantee Trustee.

         (d) If no Successor Guarantee Trustee shall have been appointed and
accepted appointment as provided in this Section 5 within 60 days after
delivery to the Additional Guarantor of an instrument of resignation, the
resigning Guarantee Trustee may petition any court of competent jurisdiction for
appointment of a Successor Guarantee Trustee. Such court may thereupon, after
prescribing such notice, if any, as it may deem proper, appoint a Successor
Guarantee Trustee.

         SECTION 6. Additional Guarantee.

         (a) The Additional Guarantor irrevocably and unconditionally
guarantees, on a subordinated basis as provided herein, the Original Guarantor's
obligations to pay in full to the Holders the Guarantee Payments (without
duplication of amounts theretofore paid by the Trust or the Original Guarantor),
as and when due, regardless of any defense, right of set-off or counterclaim
that the Trust or the Original Guarantor may have or assert (the "Additional
Guarantee"). The Additional Guarantor's obligation to make a Guarantee Payment
may be satisfied by direct payment of the required amounts by the Additional
Guarantor to the Holders or by causing the Trust or the Original Guarantor to
pay such amounts to the Holders.

         (b) The Additional Guarantor hereby waives notice of acceptance of this
Agreement and of any liability to which it applies or may apply, presentment,
demand for payment, any right to require a proceeding first against the Trust or
the Original Guarantor or any other Person before proceeding against the
Additional Guarantor, protest, notice of nonpayment, notice of dishonor, notice
of redemption and all other notices and demands.

         (c) The obligations, covenants, agreements and duties of the Additional
Guarantor under this Agreement shall in no way be affected or impaired by reason
of the happening from time to time of any of the following:

                  (i) the release or waiver, by operation of law or otherwise,
         of the performance or observance by the Trust or the Original Guarantor
         of any express or implied agreement, covenant, term or condition
         relating to the Preferred Securities to be performed or observed by the
         Trust or the Original Guarantor;

                                       6
<PAGE>   7

                  (ii) the extension of time for the payment by the Trust of all
         or any portion of the Distributions, Redemption Price, Liquidation
         Distribution or any other sums payable under the terms of the Preferred
         Securities or the extension of time for the performance of any other
         obligation under, arising out of, or in connection with, the Preferred
         Securities (other than an extension of time for payment of
         Distributions, Redemption Price, Liquidation Distribution or other sum
         payable that results from the extension of any interest payment period
         on the Subordinated Notes permitted by the Indenture);

                  (iii) any failure, omission, delay or lack of diligence on the
         part of the Holders to enforce, assert or exercise any right,
         privilege, power or remedy conferred on the Holders pursuant to the
         terms of the Preferred Securities, or any action on the part of the
         Trust granting indulgence or extension of any kind;

                  (iv) the voluntary or involuntary liquidation, dissolution,
         sale of any collateral, receivership, insolvency, bankruptcy,
         assignment for the benefit of creditors, reorganization, arrangement,
         composition or readjustment of debt of, or other similar proceedings
         affecting, the Trust or any of the assets of the Trust;

                  (v) any invalidity of, or defect or deficiency in, the
         Preferred Securities;

                  (vi) the settlement or compromise of any obligation guaranteed
         hereby or hereby incurred; or

                  (vii) any other circumstance whatsoever that might otherwise
         constitute a legal or equitable discharge or defense of a guarantor, it
         being the intent of this Section that the obligations of the Additional
         Guarantor thereunder shall be absolute and unconditional under any and
         all circumstances.

         (d) There shall be no obligation of the Holders to give notice to, or
obtain consent of, the Additional Guarantor with respect to the happening of
anything set forth in Section 6(c).

         SECTION 7. Rights of Holders.

         (a) The Holders of a Majority in liquidation amount of the Securities
have the right to direct the time, method and place of conducting any proceeding
for any remedy available to the Guarantee Trustee in respect of this Agreement
or exercising any trust or power conferred upon the Guarantee Trustee under this
Agreement.

         (b) If the Guarantee Trustee fails to enforce this Agreement any Holder
may institute a legal proceeding directly against the Additional Guarantor to
enforce its rights under this Agreement, without first instituting a legal
proceeding against the Trust, the Original Guarantor, the Guarantee Trustee or
any other Person.

                                       7
<PAGE>   8

         (c) Notwithstanding Section 7(b), any Holder may directly institute
proceedings against the Additional Guarantor to obtain Guarantee Payments in
respect of the Preferred Securities owned by such Holder, without first waiting
to determine if the Guarantee Trustee has enforced this Agreement or first
instituting a legal proceeding against the Trust, the Original Guarantor, the
Guarantee Trustee or any other Person.

         SECTION 8. Guarantee of Payment.

         This Agreement creates a guarantee of payment and not of collection.

         SECTION 9. Subrogation.

         The Additional Guarantor shall be subrogated to all rights (if any) of
the Holders against the Trust and the Original Guarantor in respect of any
amounts paid to such Holders by the Additional Guarantor under this Agreement;
provided, however, that the Additional Guarantor shall not (except to the extent
required by mandatory provisions of law) be entitled to enforce or exercise any
right that it may acquire by way of subrogation or any indemnity, reimbursement
or other agreement, in all cases as a result of payment under this Agreement,
if, at the time of any such payment, any amounts are due and unpaid under this
Agreement. If any amount shall be paid to the Additional Guarantor in violation
of the preceding sentence, the Additional Guarantor agrees to hold such amount
in trust for the Holders and to pay over such amount to the Holders.

         SECTION 10. Independent Obligations.

         The Additional Guarantor acknowledges that its obligations hereunder
are independent of the obligations of the Trust with respect to the Preferred
Securities and the Original Guarantor with respect to the Original Guarantee,
and that the Additional Guarantor shall be liable as principal and as debtor
hereunder to make any Guarantee Payments pursuant to the terms of this Agreement
notwithstanding the occurrence of any event referred to in paragraphs (i)
through (vii) of Section 6(c) hereof.

         SECTION 11. Subordination.

         This Agreement constitutes an unsecured obligation of the Additional
Guarantor that ranks (a) pari passu with the most senior preferred or preference
stock of the Additional Guarantor outstanding on the date of this Agreement or
hereafter issued and with any guarantee now or hereafter entered into by the
Additional Guarantor in respect of any preferred or preference stock of any
Affiliate of the Additional Guarantor, (b) pari passu with the guarantees of
Additional Guarantor with respect to the obligations of the Original Guarantor
with respect to the Trust, TCI Communications Financing II ("Trust II") and TCI
Communications Financing IV ("Trust IV") and the preferred securities issued by
Trust II and Trust IV, (c) senior in right of payment to any class or series of
common stock of the Additional Guarantor or preferred or preference stock of the
Additional Guarantor ranking subordinate and junior in right of payment to the
most senior preferred

                                       8
<PAGE>   9

or preference stock of the Additional Guarantor, each as may be outstanding on
the date of this Agreement or hereafter issued, and (d) subordinate and junior
in right of payment to all other indebtedness, obligations and liabilities of
the Additional Guarantor.

         SECTION 12. Events of Default; Waiver.

         The Holders of a Majority in liquidation amount of Securities may, by
vote, on behalf of the Holders of all of the Preferred Securities, waive any
past Event of Default (defined below) and its consequences. For purposes of this
Agreement, "Event of Default" means a default by the Additional Guarantor on any
of its payment or other obligations under this Agreement. Upon such waiver, any
such Event of Default shall cease to exist, and any Event of Default arising
therefrom shall be deemed to have been cured, for every purpose of this
Agreement, but no such waiver shall extend to any subsequent or other default or
Event of Default or impair any right consequent thereon.

         SECTION 13. Events of Default; Notice

         (a) The Guarantee Trustee shall, within 90 days after the occurrence of
an Event of De fault, transmit by mail, first class postage prepaid, to the
Holders, notices of all Events of Default known to the Guarantee Trustee, unless
such defaults have been cured before the giving of such notice; provided, that
the Guarantee Trustee shall be protected in withholding such notice if and so
long as the board of directors, the executive committee, or a trust committee of
directors and/or Responsible Officers of the Guarantee Trustee in good faith
determines that the withholding of such notice is in the interests of the
Holders.

         (b) The Guarantee Trustee shall not be deemed to have knowledge of any
Event of Default unless the Guarantee Trustee shall have received written
notice, or a Responsible Officer charged with the administration of the
Declaration shall have obtained written notice, of such Event of Default.

         SECTION 14. Termination.

         This Agreement shall terminate and be of no further force and effect
upon the earliest to occur of (i) the full payment of the Redemption Price of
all of the Preferred Securities, (ii) the distribution of the Subordinated Notes
to the Holders of all of the Preferred Securities or (iii) full payment of the
amounts payable in accordance with the Declaration upon liquidation of the
Trust. Notwithstanding the foregoing, this Agreement will continue to be
effective or will be reinstated, as the case may be, if at any time any Holder
must restore payment of any sums paid under the Preferred Securities, the
Original Guarantee or under this Agreement.

                                       9
<PAGE>   10

         SECTION 15. Successors and Assigns.

         All guarantees and agreements contained in this Agreement shall bind
the successors, assigns, receivers, trustees and representatives of the
Additional Guarantor, and shall inure to the benefit of the Holders of the
Preferred Securities then outstanding.

         SECTION 16. Notices.

         All notices provided for herein shall be in writing, duly signed by the
party giving such notice, and shall be delivered, telecopied or mailed by first
class mail as follows:

                  (a) if given to the Additional Guarantor, to the Additional
Guarantor's mailing address set forth below or such other address as the
Additional Guarantor may give notice of to the Holders:

                           AT&T Corp.
                           32 Avenue of the Americas
                           New York, New York 10013-2412
                                    Attn: Legal Department;

                  (b) if given to the Guarantee Trustee, to the address set
forth in the Original Guarantee Agreement or to such other address as the
Guarantee Trustee may give notice of to the Holders; and

                  (c) if given to any Holder, at the address set forth on the
books and records of the Trust.

         All such notices shall be deemed to have been given when received in
person, telecopied with receipt confirmed, or mailed by first class mail,
postage prepaid except that if a notice or other document is refused delivery or
cannot be delivered because of a changed address of which no notice was given,
such notice or other document shall be deemed to have been delivered on the date
of such refusal or inability to deliver.

         SECTION 17. Benefit.

         This Agreement is solely for the benefit of the Holders and, subject to
Section 2(a), is not separately transferable from the Preferred Securities.

         SECTION 18. Not Responsible for Recitals or Issuance of Additional
Guarantee.

         The recitals contained in this Agreement shall be taken as the
statements of the Original Guarantor and the Additional Guarantor, and the
Guarantee Trustee does not assume any responsibility for their correctness. The
Guarantee Trustee makes no representations as to the validity or sufficiency of
this Agreement.

                                       10
<PAGE>   11

         SECTION 19. Amendments.

         Except with respect to any changes that, in the opinion of the board of
directors of the Additional Guarantor, do not adversely affect the rights of
Holders (in which case no consent of Holders will be required), this Agreement
may only be amended with the prior approval of the Holders of at least a
Majority in liquidation amount of the Securities. The provisions of Section 12.2
of the Declaration of the Trust with respect to meetings of Holders of the
Securities apply to the giving of such approval.

         SECTION 20. GOVERNING LAW.

         THIS AGREEMENT SHALL BE GOVERNED BY AND CONSTRUED AND INTERPRETED IN
ACCORDANCE WITH THE INTERNAL LAWS OF THE STATE OF NEW YORK.

         SECTION 21. No Recourse Against Certain Persons.

         No past, present or future director, officer, employee or stockholder,
as such, of the Additional Guarantor or any successor thereof shall have any
liability for any obligations of the Additional Guarantor under this Agreement
or for any claim based on, in respect of, or by reason of, such obligations or
their creation and all such liability is hereby waived and released. Such waiver
and release are part of the consideration for the issue of this Agreement.

                                       11
<PAGE>   12

         IN WITNESS WHEREOF, the undersigned have executed this Agreement as of
the date first written above.

                           AT&T BROADBAND, LLC, as Original Guarantor

                           By:
                              -----------------------------
                           Name:
                           Title:

                           AT&T Corp., as Additional Guarantor

                           By:
                              -----------------------------
                           Name:
                           Title:

                           THE BANK OF NEW YORK, as Guarantee Trustee

                           By:
                              -----------------------------
                           Name:
                           Title:

                                       12

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