Smith Micro Software (SMSI) S-3/A Shelf registration (amended)

October 27, 2006



Smith Micro Software, Inc.
51 Columbia, Suite 200
Aliso Viejo, California 92656

Re: Smith Micro Software, Inc.—Registration Statement on Form S-3

Ladies and Gentlemen:

In connection with Amendment No. 1 to the Registration Statement on Form S-3 (the “Registration Statement”) filed by Smith Micro Software, Inc., a Delaware corporation (the “Company”), with the Securities and Exchange Commission (the “Commission”) on October 27, 2006 under the Securities Act of 1933, as amended (the “Securities Act”), you have requested our opinion with respect to the matters set forth below.

You have provided us with a draft of the Registration Statement in the form in which it will be filed, which includes the prospectus (the “Prospectus”). The Prospectus provides that it will be supplemented in the future by one or more supplements to the Prospectus (each, a “Prospectus Supplement”). The Prospectus as supplemented by various Prospectus Supplements will provide for the registration by the Company of (i) up to $91,710,000 in shares of the Company’s common stock, $0.001 par value per share, (the “Company Shares”) which may be issued from time to time by the Company on a continuous or delayed basis pursuant to Rule 415 under the Securities Act, and (ii) an aggregate of up to 500,000 shares of the Company’s common stock, $0.001 par value per share, (the “Stockholder Shares”, and together with the Company Shares, the “Shares”), that may be sold by certain selling stockholders.

As counsel to the Company, we are familiar with the proceedings taken and proposed to be taken by the Company in connection with the issuance and sale of the Shares. For the purposes of this opinion, we have assumed that such proceedings to be taken in the future will be timely completed in the manner presently proposed and that the terms of each issuance will otherwise be in compliance with law. In addition, we have examined such matters of fact and questions of law as we have considered appropriate for purposes of rendering this opinion.

When the Registration Statement and any required post-effective amendments thereto have all become effective under the Securities Act and any and all Prospectus Supplement(s) required by applicable laws have been delivered and filed as required by such laws, and upon adoption by the Board of Directors of the Company of a resolution in form and content as

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required by applicable law authorizing the issuance of the Company Shares and upon issuance and delivery of and payment of legal consideration not less than the par value thereof for the Company Shares in the manner contemplated by the Registration Statement, the Prospectus and the related Prospectus Supplement(s) and by such resolution, and assuming that (i) the terms of the Company Shares as issued and delivered are as described in the Registration Statement, the Prospectus and the related Prospectus Supplement(s) and such resolution, (ii) at the time of issuance of the Company Shares, the Company has a sufficient number of authorized but unissued shares under its Amended and Restated Certificate of Incorporation and (iii) such shares are then issued and sold as contemplated in the Registration Statement, the Prospectus and the related Prospectus Supplement(s), and such resolution, the Company Shares will be validly issued, fully paid and nonassessable.

The Stockholder Shares are validly issued, fully paid and nonassessable.

We express no opinion as to matters governed by laws of any jurisdiction other than the laws of the General Corporation Law of the State of Delaware and the federal laws of the United States of America, as in effect on the date hereof.

We hereby consent to the use of our name under the heading “Legal Matters” in the Registration Statement to be filed by the Company with the Commission. We further consent to your filing a copy of this opinion as Exhibit 5.1 to the Registration Statement. In giving such permission, we do not admit hereby that we come within the category of persons whose consent is required under Section 7 of the Securities Act, or the rules and regulations of the Commission thereunder. We disclaim any undertaking to advise you of any subsequent changes of the facts stated or assumed herein or any subsequent changes in applicable law.

Very truly yours,

/s/ Morrison & Foerster LLP