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                                                                   EXHIBIT 10.42

                                    GUARANTY

            This Guaranty ("Guaranty") is effective as of the 23 day of
July, 1999, by and between Nextel International, Inc. (hereinafter referred
to as "Guarantor"), in favor of Motorola, Inc., a Delaware corporation
(hereinafter referred to as "Motorola").

            WHEREAS, Guarantor, by and through its affiliates, is the owner of
approximately 62% of the issued and outstanding shares of the capital stock of
Nextel del Peru, S.A., a Peruvian company (hereinafter referred to as the
"Company"); and

            WHEREAS, Motorola and Company have entered into a Subscriber Unit
Purchase Agreement dated as of July 23, 1999 (the "Purchase Agreement")
covering the supply of certain iDEN subscriber handset equipment and services
for a mobile communications system in Lima, Peru; and

            WHEREAS, Motorola has agreed, under certain circumstances, [*]; and

            WHEREAS, [*]; and

            NOW THEREFORE, in consideration of the mutual covenants herein
contained and for other good and valuable consideration, the receipt and
sufficiency of which are hereby acknowledged by Guarantor, the Guarantor does
hereby covenant and agree as follows:

            1. The Guarantor hereby unconditionally and irrevocably guarantees
the full and prompt performance of all payment obligations of the Company under
the Purchase Agreement, without deduction for any claim of setoff or
counterclaim, including the entire outstanding balance due under the Purchase
Agreement together with accrued interest, delinquency charges, and any other
charges cost and expenses provided for thereunder. If any amounts for federal,
state and/or local excise, sales, use, property, retailer's, occupation or any
other assessment in the nature of taxes however designated, on the products
and/or services provided under the Purchase Agreement (exclusive however, of any
taxes measured by net income or taxes based on Motorola's gross receipts or
based on Motorola's franchise), are determined to be applicable to the
transactions set forth in the Purchase Agreement or this Guaranty, or to the
extent Motorola is required to pay or bear the burden thereof, one hundred
percent (100%) thereof shall be added to the amounts guaranteed hereunder.
Personal property taxes assessed on the products and/or services provided under
the Purchase Agreement after the date title transfers to Company under the terms
and conditions of the Purchase Agreement, shall be the responsibility of
Company, and shall be guaranteed by Guarantor

                                        1

     * Confidential portions omitted and filed separately with the Commission
pursuant to an application for confidential treatment pursuant to Rule 24b-2
under the Securities and Exchange Act of 1934, as amended.
<PAGE>   2

pursuant to the terms and conditions hereof. In the event Company and/or
Guarantor claims exemption from sales, use or other such taxes under the
Purchase Agreement or hereunder, Guarantor shall indemnify and hold Motorola
harmless for any such assessments levied by a proper taxing authority for such
taxes, including interest, penalties, and late charges pursuant to the terms and
conditions hereof, to the extent such indemnity is not provided by Company to
Motorola pursuant to the terms of the Purchase Agreement. Each such payment
shall payable to Motorola or its assignee at its principal offices. Guarantor's
obligations hereunder shall not be subject to any reduction, limitation,
impairment or termination for any reason, including but not limited to, any
claim of waiver, release, surrender, alteration or compromise, and shall not be
subject to any defense or setoff, counterclaim, recoupment or termination
whatsoever by reason of any of the following: (a) the invalidity or
unenforceability of the Purchase Agreement; (b) any extension, modification or
renewal of, or indulgence with respect to, or substitutions for, the sums owed
under the Purchase Agreement or any part thereof or any agreement relating
thereto at any time; (c) any failure or omission to enforce any right, power or
remedy with respect to the Purchase Agreement or any part thereof; (d) any
waiver of any right, power or remedy or of any default with respect to the
Purchase Agreement or any part thereof or any other agreement relating thereto;
or (e) any compromise, settlement, waiver or other modification, or any release
or surrender not knowingly given by Motorola, with or without consideration, of
the Purchase Agreement, any guarantees with respect to the Purchase Agreement or
any part thereof or any other obligation of any person or entity with respect to
the Purchase Agreement or any part thereof.

            2. As long as the Purchase Agreement is outstanding, Guarantor
agrees that this Guaranty shall be an absolute, present, continuing, unlimited,
unconditional and irrevocable guaranty of payment (and not of collection). Suit
may be brought and maintained against the Guarantor by Motorola to enforce any
liability, obligation or duty guaranteed hereunder without joinder of any other
person or entity. The liability of Guarantor shall not be deemed to be waived,
released, discharged, impaired or affected by: any foreclosures, indulgence, or
variation of terms of the Purchase Agreement whether or not it might vary the
risk of guaranty under this Guaranty, including, without limitation, any
alteration, amendment, acceleration, extension, modification, waiver or change
concerning the amount of time or manner of payment or performance of any of the
obligations; any discharge or release of any of the obligations securing the
payment or performance thereof, whether or not in accordance with the respective
provisions thereof, or any bankruptcy, insolvency, reorganization, liquidation
or similar proceeding concerning Guarantor; the addition or omission or delay in
the enforcement of any right or remedy with respect to any of the obligations or
with respect to this Guaranty; or the receipt, exchange, surrender or
acquiescence in, any default with respect to any of the obligations.

            3. Guarantor represents and warrants to Motorola as follows:

            (a) Guarantor is an indirect shareholder of the Company and owns,
through its affiliates, approximately 62% of the issued and outstanding capital
stock thereof, and as

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such, Guarantor has received legally sufficient consideration in connection with
the transactions referenced herein to make this Guaranty legally and equitably
enforceable against Guarantor;

            (b) Guarantor is a corporation duly organized, validly existing and
in good standing under the laws of its jurisdiction of incorporation and has the
corporate power and authority to own its properties and to carry on its
business;

            (c) Guarantor has the corporate power to execute and deliver this
Guaranty and to perform its obligations hereunder. The execution, delivery and
performance of this Guaranty by Guarantor has been duly authorized by all
requisite corporate action and the same will not violate any provision of law or
any order of any court or governmental agency applicable to Guarantor or the
articles of organization and/or by-laws of Guarantor;

            (d) The execution, delivery and performance by Guarantor of this
Guaranty will not violate the terms of any instrument, document or agreement to
which Guarantor is a party, either individually or jointly, with any other
person, firm, entity or corporation or by which Guarantor or any of the property
of Guarantor is bound, or be in conflict with, result in a breach of, or
constitute (with giving of notice or lapse of time or both) a default under any
such instrument, document or agreement, or result in the creation or imposition
of any lien upon any of the property or assets of Guarantor; and

            (e) This Guaranty constitutes the valid and legally binding
obligation of Guarantor, enforceable in accordance with its terms and no
material consent, approval or authorization of any governmental authority,
bureau or agency is required in connection with the execution, delivery or
performance of this Guaranty by Guarantor, or with the validity and
enforceability of this Guaranty as to Guarantor.

            4. This Guaranty is, and shall be deemed to be, a contract entered
into, under and pursuant to the substantive laws of the State of Illinois,
United States of America, without regard to the conflict of laws rules thereof.

            5. Guarantor agrees that if Motorola shall employ outside legal
counsel in order to successfully present, enforce or defend any or all of
Motorola's rights or remedies hereunder, then in any such event, Guarantor shall
pay all reasonable attorneys' fees and reasonable expenses incurred by Motorola
in connection therewith.

            6. Any notices, requests, demands or other communications required
or permitted to be given to any party hereunder shall be deemed to have been
sufficiently given or served for all purposes when either: (i) presented
personally; or (ii) if sent by facsimile, upon transmittal with confirmed
answerback; or (iii) upon post office's confirmation of receipt (or refusal of
delivery) by the addressee, if sent by prepaid certified mail or via overnight
courier, return receipt requested, to any party hereto at its address shown
below, or at such other address of which it shall have notified in writing the
party giving such notice.

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            Nextel International, Inc.
            2003 Edmund Halley Drive
            Reston, Virginia  20191
            Telephone No.:  703-433-8427
            Facsimile No.:  703-433-8435
            Attention:  Chief Financial Officer

            Motorola, Inc.
            1301 East Algonquin Road
            Schaumburg, Illinois  60196-1079
            Telephone No.:  (847) 538-4983
            Facsimile No. (847) 538-2279
            Attn: Global Finance Group

            7. This Guaranty may not be amended or modified except by a
modification in writing signed by Guarantor and Motorola.

            8. All of the terms, agreement and conditions of this Guaranty shall
extend to and be binding upon Guarantor, its successors and assigns, and shall
inure to the benefit of Motorola and its respective successors and assigns.
Guarantor acknowledges that time is of the essence. Guarantor acknowledges and
agrees that this Guaranty and Motorola's rights and benefits hereunder, are
freely assignable and transferable by Motorola.

            9. Guarantor waives presentment, protest, notice of protest and
notice of either dishonor, default or nonperformance in connection with the
Purchase Agreement or with respect to any other obligations thereunder or under
this Guaranty to the extent it may lawfully do so, and any and all demands and
other notice of every kind that may be required to be given by law.

            10. Any determination that any provision hereof is invalid, illegal
or unenforceable in any respect shall not affect the validity, legality or
enforceability of such provision in any other respect and shall not affect the
validity, legality or enforceability of any other provision contained herein.

            11. This Guaranty shall be effective upon the date of execution
hereof and the obligations of the Guarantor shall continue until the receipt by
Motorola of payment in full (principal and accrued interest) of sums due under
the Purchase Agreement.

            12. In the event Guarantor is caused to make payment hereunder,
Guarantor waives any rights of subrogation as against the Company until all
amounts payable by Company have been paid in full to Motorola.

            13. Guarantor acknowledges that it has or may have in the future
other guaranteed obligations in favor of Motorola and/or its affiliates and
subsidiaries, and

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Guarantor agrees that nothing herein shall in any way modify, amend, or alter
the terms and conditions of any other guarantee made by Guarantor.

                                      NEXTEL INTERNATIONAL, INC.

                                      Title: Vice President and Treasurer
                                      By:  /s/ Michel A. Buhler

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                                                                   EXHIBIT 10.43

                       SUBSCRIBER UNIT PURCHASE AGREEMENT
                    FOR INFOCOM COMMUNICATIONS NETWORK, INC.

            This Agreement is entered into between Motorola, Inc., by and
through its iDEN Subscriber Group, having a place of business at 8000 West
Sunrise Boulevard; Ft. Lauderdale, Florida 33322 (hereinafter "Seller" or
"MOTOROLA") and Infocom Communications Network, Inc., a company formed under the
laws of the Philippines, with a place of business at 20 FLR Centerpoint
Building, Julia Vargas Avenue, Ortigas Manila, Pasiq City 1600 Philippines
(hereinafter, together with any wholly-owned subsidiary previously accepted by
the Seller, collectively known as "Buyer").

            This agreement applies only for sales of Motorola iDEN subscriber
products for distribution outside of the United States. Buyer agrees to purchase
and Seller agrees to sell selected Motorola iDEN subscriber products
manufactured in Seller's facilities in Plantation, Florida, U.S.A., (hereinafter
"Products") during a term beginning on the date of the last signature hereto
("Effective Date"), and ending April 30, 2000 ("Initial Term"), under the terms
and conditions set forth in this Agreement. Buyer may purchase products
manufactured at Seller's other facilities under terms and conditions acceptable
to both parties at the time such purchases are desired.

PURCHASE ORDERS. All orders by Buyer shall be only upon the terms and conditions
of this Agreement. The only effect of any terms and conditions in Buyer's orders
or elsewhere shall be to request the time and number of units to be delivered,
subject to Seller's acceptance, but they shall not change, alter or add to the
terms and conditions of this Agreement in any other way. Except as provided
below, Seller's invoice shall also not change the terms and conditions of this
Agreement. Cancellation charges which shall include all costs incurred or
committed for may apply for any cancelled order. Seller shall use its reasonable
best efforts, including shipment to other Nextel properties, to mitigate any
costs incurred as a result of the Buyer's cancellation of an order within the
non-cancelable period. Purchase orders are non-cancelable fifteen (15) days or
less before requested ship date.

PRICING. Contract prices for Products require firm and prosecutable orders
thirty (30) days prior to requested ship date. Prices applicable to Products
sold pursuant to this Agreement ("Prices") are those negotiated from time to
time by Nextel Communications, Inc. and Motorola, Inc. In order for Prices to be
applicable, the purchase orders submitted to Seller must reference this
Agreement.

PAYMENT TERMS AND CONDITIONS. Seller will invoice Buyer for the Products on or
about the date of shipment thereof. Payment of each invoiced amount is due
within 30 days of the date of the invoice; [*]. The Buyer may prepay any
invoice, in part or in full, without penalty or premium at any time.

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     * Confidential portions omitted and filed separately with the Commission
pursuant to an application for confidential treatment pursuant to Rule 24b-2
under the Securities and Exchange Act of 1934, as amended.

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[*]

[*]

FORECASTS. During the term of this Agreement, Buyer shall provide Seller, [*] a
continuous usage forecast for [*] to assist Seller in maintaining an orderly
production flow for the purpose of Buyer's delivery requirements. Buyer shall
state in the [*] Forecast the Product model numbers and projected purchase
volume by units for [*]. The [*] Forecast does not constitute a commitment by
the Buyer; however, Buyer's failure to provide such information may be
considered cause by Seller for excusable delivery delay.

DELIVERY AND TITLE. All deliveries are FCA Seller's plant, Plantation, Florida
USA. Each such delivery will be separately invoiced. DELIVERY DATES ARE BEST
ESTIMATES ONLY. Title to the Products will pass to Buyer at the Seller's plant,
Plantation, Florida.

FORCE MAJEURE. Neither party shall be liable for any delay or failure to perform
due to any cause beyond its reasonable control. Causes include, but are not
limited to strikes, acts of God, acts of the other party, interruptions of
transportation or inability to obtain necessary labor, materials or facilities,
or default of any supplier, or delays in regulatory authorization or license
grant. The delivery schedule shall be considered extended by a period of time
equal to the time lost because of any excusable delay. In the event either party
is unable to wholly or partially perform for a period greater than forty-five
(45) days because of any cause beyond its reasonable control, either party may
terminate any delayed order without any liability.

LICENSE DISCLAIMER. Nothing contained herein shall be deemed to grant either
directly or by implication, estoppel, or otherwise, any license under any
patents, copyrights, trademarks or trade secrets of SELLER.

TAXES. Except for the amount, if any, of specific taxes stated in the Agreement,
Prices are exclusive of any amount for Federal, State and/or Local excise,
sales, use, property, retailer's, occupation or any other assessment in the
nature of taxes however designated, on the Products and/or services provided
under this Agreement. If any such excluded tax, exclusive however, of any taxes
measured by Seller's net income or taxes based on Seller's gross receipts or
based on Seller's franchise, is determined to be applicable to this transaction
or to the extent Seller is required to pay or bear the burden thereof, one
hundred percent (100%) thereof shall be added to the Prices and paid by Buyer.
Personal property taxes assessed on the Products after the date title transfers
under this paragraph, shall be the responsibility of Buyer. In the event Buyer
claims exemption from sales, use or other such taxes under this Agreement, Buyer
shall hold Seller harmless of any subsequent assessments levied by a proper
taxing authority for such taxes, including interest, penalties, and late
charges.

Upon Seller's request, Buyer shall produce sufficient evidence within thirty
(30) days of such request to prove that Buyer has fulfilled its obligation
relating to all taxes, duties, and fees. If any such taxes, duties, or fees are
determined to be applicable to this transaction and notwithstanding Buyer's
responsibility, Seller is required to pay or bear the burden thereof, then
Prices shall be increased by the amount of such taxes and any interest or
penalty, and Buyer shall pay to Seller the full amount of any such increase no
later than thirty (30) days after receipt of an invoice.

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     * Confidential portions omitted and filed separately with the Commission
pursuant to an application for confidential treatment pursuant to Rule 24b-2
under the Securities and Exchange Act of 1934, as amended.
<PAGE>   3

Customs clearance, or related costs pertaining to import of the Products are the
responsibility of Buyer. No such costs have been included in Seller's Prices.

TECHNICAL ASSISTANCE. Seller's warranty shall not be enlarged, and no obligation
or liability shall arise out of Seller's rendering of technical advice,
facilities or service in connection with Buyer's purchase of the Products
furnished.

LIMITATION OF LIABILITY. SELLER'S TOTAL LIABILITY, WHETHER FOR BREACH OF
CONTRACT, WARRANTY, NEGLIGENCE, STRICT LIABILITY IN TORT OR OTHERWISE, IS
LIMITED TO THE PRICE OF THE PARTICULAR PRODUCTS SOLD HEREUNDER WITH RESPECT TO
WHICH LOSSES OR DAMAGES ARE CLAIMED. BUYER'S SOLE REMEDY IS TO REQUEST SELLER AT
SELLER'S OPTION TO EITHER REFUND THE PURCHASE PRICE, REPAIR OR REPLACE PRODUCT
(S) THAT ARE NOT AS WARRANTED. IN NO EVENT WILL SELLER BE LIABLE FOR ANY LOSS OF
USE, LOSS OF TIME, INCONVENIENCE, COMMERCIAL LOSS, LOST PROFITS OR SAVINGS OR
OTHER INCIDENTAL OR CONSEQUENTIAL DAMAGES TO THE FULL EXTENT SUCH MAY BE
DISCLAIMED BY LAW.

LOGOS AND TRADEMARKS. In order that Seller may protect its trademarks, trade
names, corporate slogans, corporate logo, goodwill and product designations,
Buyer, without the express written consent of Seller, shall have no right to use
any such marks, names, slogans or designations of Seller in the sales, lease or
advertising of any products or on any product container, component part,
business forms, sales, advertising and promotional materials or other business
supplies or material, whether in writing, orally or otherwise. Buyer agrees to
provide Motorola with advertising material containing any Motorola marks for
approval before such marks are used. Motorola agrees to review Buyer's
advertising material in a reasonable time and to not unreasonably withhold
approval thereof. To minimize the impact of this review on the Buyer, Motorola
will provide Buyer with guidelines on the use of Motorola logos. Compliance with
these guidelines shall serve to relieve Buyer from having to submit
advertisements for prior approval.

PARTY RELATIONSHIP. This Agreement does not create any agency, joint venture or
partnership between Buyer and Seller. Buyer shall not impose or create any
obligation or responsibility, express or implied, or make any promises,
representations or warranties on behalf of Seller, other than as expressly
provided herein.

WAIVER. The failure of either party to insist in any one or more instances, upon
the performance of any of the terms or conditions herein or to exercise any
right hereunder shall not be construed as a waiver or relinquishment of the
future performance of any such terms or conditions or the future exercise of
such right but the obligation of the other party with respect to such future
performance shall continue in full force and effect.

DEFAULT. In the event that either party shall be in breach or default of any of
the terms or conditions of this Agreement and such breach or default shall
continue for a period of thirty (30) days after the giving of written notice by
the non-defaulting party, then subject to the other terms and conditions of this
Agreement, the non-defaulting party, in addition to other rights and remedies it
may have in law or equity, shall have the right to immediately cancel this
Agreement without any charge or liability whatsoever.

DISPUTE RESOLUTION. The parties agree that any claims or disputes will be
submitted to non-binding mediation prior to initiation of any formal legal
process. Costs of mediation will be shared equally.

WARRANTY. The warranty document supplied with the Product at the time of
shipping shall govern the warranty coverage provided under this Agreement.

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GENERAL. This Agreement constitutes the entire and final expression of agreement
between the parties pertaining to the subject matter hereof and supersedes all
other communications, oral or written, between the parties. No alterations or
modifications of this Agreement shall be binding upon either Buyer or Seller
unless made in writing and signed by an authorized representative of each. If
any term or condition of this Agreement shall to any extent be held by a court
or other tribunal to be invalid, void or unenforceable, then that term or
condition shall be inoperative and void insofar as it is in conflict with law,
but the remaining rights and obligations of the parties shall be construed and
enforced as if this Agreement did not contain the particular term or condition
held to be invalid, void or unenforceable. Buyer shall make no assignment of
this Agreement or of any right granted herewith without the prior written
consent of SELLER. Any assignment of this Agreement is null and void. The laws
of the State of Illinois of the United States shall govern this Agreement.

            Unless this Agreement is superseded by a new agreement, or otherwise
terminated pursuant to the terms contained herein, this Agreement will continue
in effect beyond its Initial Term until terminated by either party upon thirty
(30) days prior written notice.

            IN WITNESS WHEREOF, the parties have caused this Agreement to be
executed by their duly authorized representatives effective as of the 4
day of August, 1999.

       SELLER:                                        BUYER:

       MOTOROLA, INC.                                INFOCOM COMMUNICATIONS
                                                     NETWORK, INC.

By:    /s/ Mark Shockley                         By: /s/ Antonio M. Urrera
       -------------------------------------         ------------------------
       Signature                                     Signature

Printed Name: MARK SHOCKLEY                      Printed Name: Antonio M. Urrera
                                                               -----------------

Title: Vice President & General Manager          Title: President and Chief
       iDEN International Markets Division              Executive Officer
       iDEN Subscriber Group                            ----------------------

Date:  August 4, 1999                            Date: August 4, 1999
       -------------------------------------          -----------------------

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