[form of Exchange Agent Agreement

FORM OF EXCHANGE AGENT AGREEMENT]


As of __________, 1997


The Bank of New York Corporate Trust Trustee Administration 101 Barclay Street, 21st Floor New York, New York 10286


Ladies and Gentlemen:


CellNet Data Systems, Inc. (the "Company") proposes to make an offer (the "Exchange Offer") to exchange its 14% Senior Discount Notes due 2007, Series A (the "Old Securities") for its 14% Senior Discount Notes due 2007, Series B (the "New Securities"). The terms and conditions of the Exchange Offer as currently contemplated are set forth in a prospectus, dated __________, 1997 (the "Prospectus"), proposed to be distributed to all record holders of the Old Securities. The Old Securities and the New Securities are collectively referred to herein as the "Securities."


The Company hereby appoints The Bank of New York to act as exchange agent (the "Exchange Agent") in connection with the Exchange Offer. References hereinafter to "you" shall refer to The Bank of New York.


The Exchange Offer is expected to be commenced by the Company on or promptly after the effective date of the Form S-4 Registration Statement filed by the Company with the Securities Exchange Commission on October 15, 1997. The Letter of Transmittal accompanying the Prospectus (or in the case of book-entry securities, the ATOP system) is to be used by the holders of the Old Securities to accept the Exchange Offer and contains instructions with respect to the delivery of certificates for Old Securities tendered in connection therewith.


The Exchange Offer shall expire at 5:00 P.M., New York City time, on the date specified in the Prospectus or on such later date or time to which the Company may extend the Exchange Offer (the "Expiration Date"). Subject to the terms and conditions set forth in the Prospectus, the Company expressly reserves the right to extend the Exchange Offer from time to time and may extend the Exchange Offer by giving oral (confirmed in writing) or written notice to you before 9:00 A.M., New York City time, on the business day following the previously scheduled Expiration Date.


The Company expressly reserves the right to amend or terminate the Exchange Offer, and not to accept for exchange any old Securities not theretofore accepted for exchange, upon the occurrence of any of the conditions of the Exchange Offer specified in the Prospectus under the caption "The Exchange Offer--Conditions." The Company will give oral (confirmed in writing) or written notice of any amendment, termination or nonacceptance to you as promptly as practicable.


In carrying out your duties as Exchange Agent, you are to act in accordance with the following instructions:


1. You will perform such duties and only such duties as are specifically set forth in the section of the Prospectus captioned "The Exchange Offer", or as specifically set forth herein; PROVIDED, HOWEVER, that in no way will your general duty to act in good faith be discharged by the foregoing.


2. You will establish an account with respect to the Old Securities at The Depository Trust Company (the "Book-Entry Transfer Facility") for purposes of the Exchange Offer within two business days after the date of the Prospectus, and any financial institution that is a participant in the Book-Entry Transfer Facility's systems may make book-entry delivery of the Old Securities by causing the Book-Entry Transfer Facility to transfer such Old Securities into your account in accordance with the Book-Entry Transfer Facility's procedure for such transfer.


3. You are to examine each of the Letters of Transmittal and certificates for Old Securities (or confirmation of book-entry transfer into your account at the Book-Entry Transfer Facility) and any other documents delivered or mailed to you by or for holders of the Old Securities to ascertain whether: (i) the Letters of Transmittal and any such other documents are duly executed and properly completed in accordance with instructions set forth therein and (ii) the Old Securities have otherwise been properly tendered. In each case where the Letter of Transmittal or any other document has been improperly completed or executed or any of the certificates for Old Securities are not in proper form for transfer or some other irregularity in connection with the acceptance of the Exchange Offer exists, you will endeavor to inform the presenters of the need for fulfillment of all requirements and to take any other action as may be necessary or advisable to cause such irregularity to be corrected.


4. With the approval of the President, Senior Vice President, Executive Vice President, or any Vice President of the Company (such approval, if given orally, to be confirmed in writing) or any other party designated by such an officer in writing, you are authorized to waive any irregularities in connection with any tender of Old Securities pursuant to the Exchange Offer.


5. Tenders of Old Securities may be made only as set forth in the Letter of Transmittal and in the section of the Prospectus captioned "The Exchange Offer--Procedures for Tendering", and Old Securities shall be considered properly tendered to you only when tendered in accordance with the procedures set forth therein.


Notwithstanding the provisions of this paragraph 5, Old Securities which the President, Senior Vice President, Executive Vice President, or any Vice President of the Company shall approve as having been properly tendered shall be considered to be properly tendered (such approval, if given orally, shall be confirmed in writing).


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6. You shall advise the Company with respect to any Old Securities received subsequent to the Expiration Date and accept its instructions with respect to disposition of such Old Securities.


7. You shall accept tenders:


(a) in cases where the Old Securities are registered in two or more names only if signed by all named holders;


(b) in cases where the signing person (as indicated on the Letter of Transmittal) is acting in a fiduciary or a representative capacity only when proper evidence of his or her authority so to act is submitted; and


(c) from persons other than the registered holder of Old Securities provided that customary transfer requirements, including any applicable transfer taxes, are fulfilled.


You shall accept partial tenders of Old Securities where so indicated and as permitted in the Letter of Transmittal and deliver certificates for Old Securities to the transfer agent for split-up and return any untendered Old Securities to the holder (or such other person as may be designated in the Letter of Transmittal) as promptly as practicable after expiration or termination of the Exchange Offer.


8. Upon satisfaction or waiver of all of the conditions to the Exchange Offer, the Company will notify you (such notice if given orally, to be confirmed in writing) of its acceptance, promptly after the Expiration Date, of all Old Securities properly tendered and you, on behalf of the Company, will exchange such Old Securities for New Securities and cause such Old Securities to be canceled. Delivery of New Securities will be made on behalf of the Company by you at the rate of $1,000 principal amount of New Securities for each $1,000 principal amount of the corresponding series of Old Securities tendered promptly after notice (such notice if given ...