SUMMARY

This summary highlights selected information from this proxy statement/prospectus. It may not contain all of the information that is important to you. You are urged to carefully read the entire proxy statement/prospectus and the other documents referred to in this proxy statement/prospectus because the information in this section does not provide all the information that might be important to you with respect to the merger agreement, the merger transaction and the other matters being considered at the special meeting. For additional information, see “Where You Can Find More Information” beginning on page 281. Each item in this summary refers to the page of this proxy statement/prospectus on which that subject is discussed in more detail.

Information about the Companies (page 134)

Calix, Inc.

Calix Inc., or Calix, is a leading provider in North America of broadband communications access systems and software for copper- and fiber- based network architectures that enable communications service providers, or CSPs, to connect to their residential and business subscribers. Calix develops and sells carrier-class hardware and software products, which is referred to as the Unified Access portfolio, designed to enhance and transform CSP access networks to meet the changing demands of subscribers rapidly and cost-effectively. The Unified Access portfolio consists of Calix’s two core platforms, the C-Series multiservice, multiprotocol access platform, or C-Series platform, and the E-Series Ethernet service access platforms and nodes, or E-Series platforms and nodes, along with complementary P-Series optical network terminals, or ONTs, and the Calix Management System, or CMS, network management software. Calix also offers installation, training, post-sales software support and extended warranty services. Calix’s principal executive offices are located at 1035 N. McDowell Blvd, Petaluma, California 94954 and its telephone number is (707) 766-3000.

Ocean Sub I, Inc.

Ocean Sub I, Inc., or Ocean Sub I, is a direct, wholly owned subsidiary of Calix. Ocean Sub I has not carried on any activities to date, other than activities incidental to its formation or undertaken in connection with the transactions contemplated by the merger transaction. Ocean Sub I’s principal executive offices are located at 1035 N. McDowell Blvd, Petaluma, California 94954 and its telephone number is (707) 766-3000.

Ocean Sub II, LLC

Ocean Sub II, LLC, or Ocean Sub II, is a direct, wholly owned subsidiary of Calix. Ocean Sub II has not carried on any activities to date, other than activities incidental to its formation or undertaken in connection with the transactions contemplated by the merger transaction. Ocean Sub II’s principal executive offices are located at 1035 N. McDowell Blvd, Petaluma, California 94954 and its telephone number is (707) 766-3000.

Occam Networks, Inc.

Occam Networks, Inc., or Occam, develops, markets and supports innovative broadband access products designed to enable telecom service providers to offer bundled voice, video and high speed internet, or Triple Play, services over both copper and fiber optic networks. Occam’s core product line is the Broadband Loop Carrier, or BLC, an integrated hardware and software platform that uses Internet Protocol, or IP, and Ethernet technologies to increase the capacity of local access networks, enabling the delivery of advanced Triple Play services. Occam also offers a family of ONTs for fiber optic networks, remote terminal cabinets and professional services. Occam’s principal executive offices are located at 6868 Cortona Drive, Santa Barbara, California 93117, and its telephone number is (805) 692-2900.

The Merger (page 72)

Calix and Occam agreed to the acquisition of Occam by Calix upon the terms and subject to the conditions in the merger agreement that is described in this proxy statement/prospectus. As the first step in the transaction, Ocean Sub I will merge with Occam, with Occam continuing as the surviving entity. Immediately thereafter, Occam will merge with Ocean Sub II, with Ocean Sub II continuing as the surviving corporation. The first merger is referred to as the first-step merger, the second merger is referred to as the second-step merger, the first-step merger and second-step merger are collectively referred to as the merger transaction and the effective time of the first-step merger is referred to as the effective time. For more information, please see the sections titled “Proposal One—The Merger” and “The Merger Agreement” beginning on pages 72 and 116, respectively.

Merger Consideration (page 116)

At the effective time, each share of Occam common stock, other than shares owned by Calix, Occam or any of their respective subsidiaries (which will be cancelled), will be converted into the right to receive (i) 0.2925 shares of Calix common stock and (ii) $3.8337 in cash.

Treatment of Occam Options and Other Equity Awards (page 116)

Stock Options and Restricted Stock Units. Immediately prior to the effective time, (a) each outstanding Occam stock option or restricted stock unit as of immediately prior to the effective time which was or shall become vested as of the effective time with a per share exercise price that is less than (i) $3.8337 plus (ii) 0.2925 multiplied by the average volume weighted average trading price of Calix common stock during the five consecutive trading days ending on the trading day that is one day before the effective time, such amount being referred to as the cash-out consideration, (b) certain additional Occam options or restricted stock units that may be included, depending on the number of shares of Calix common stock issuable pursuant to the merger agreement and (c) unless determined otherwise by Calix, any Occam options or restricted stock units held by persons who are not Occam employees or consultants immediately prior to the effective time will be automatically cancelled and extinguished and the vested portion thereof will be automatically converted into the right to receive the cash-out consideration for the aggregate number of shares of Occam common stock that were issuable upon the exercise of such stock options or restricted stock units, less any applicable per share exercise price. If additional equity awards are cancelled in accordance with (b) above, equity awards with the highest exercise price will be cashed out first, and for these purposes a restricted stock unit is treated as having a $0 exercise price.

Unvested portions of each outstanding Occam stock option or restricted stock unit held by employees who continue to be employed by Calix or its subsidiaries after the effective time that are not cancelled as described above will be, at the effective time, automatically converted into options or restricted stock units, as the case may be, for Calix common stock, subject to adjustments in accordance with the compensatory award exchange ratio, and will otherwise be subject to the terms and conditions of such award prior to the effective time, including vesting and exercisability.

Restricted Stock. Immediately prior to the effective time, the restrictions on each restricted stock award held by a non-employee director shall lapse and the underlying Occam common stock shall be treated in the merger in the same manner as other shares of Occam common stock.

Risk Factors (page 26)

There are risks associated with the merger transaction, which are described in the section titled “Risk Factors” beginning on page 26. You should carefully read and consider these risks, which include, without limitation, the following:

Special Meeting of Occam Stockholders (page 68)

Date, Time and Place. The special meeting of Occam stockholders will be held on [—], 2010 at [—] a.m., local time, at Occam’s offices at 3185 Laurelview Court, Fremont, California 94538.

Purpose. At the special meeting, Occam stockholders will be asked to consider and vote upon:

Record Date and Quorum. Only holders of record of Occam common stock at the close of business on [—], 2010, the record date, are entitled to notice of and to vote at the special meeting and any adjournment or postponement thereof. You will have one vote for each share of Occam common stock that you owned on the record date. As of the record date, there were [—] shares of Occam common stock outstanding and entitled to vote at the special meeting. A majority of the shares of Occam common stock issued and outstanding and entitled to vote at the special meeting being present constitutes a quorum for the purpose of considering the proposals to be voted upon at the special meeting.

Vote Required. Occam cannot complete the merger transaction unless the merger agreement is adopted by the affirmative vote of the holders of a majority of the outstanding shares of Occam common stock entitled to vote at the special meeting. The adjournment proposal must be approved by the affirmative vote of the holders of a majority of the votes cast at the special meeting on such proposal.

Occam’s Reasons for the Merger; Recommendation of the Occam Board of Directors (page 89)

At a meeting duly called and held, the Occam board has (i) unanimously determined that the merger agreement and the transactions contemplated thereby are fair to, advisable and in the best interests of the Company’s stockholders, (ii) unanimously approved and adopted the merger agreement and the transactions contemplated thereby and (iii) unanimously resolved to recommend adoption of the merger agreement and the other transactions contemplated thereby by the stockholders of Occam.

In determining whether to adopt the merger agreement and approve the transactions contemplated thereby, the Occam board considered the factors described under “Proposal One—The Merger—Occam’s Reasons for the Merger; Recommendation of the Occam Board of Directors” beginning on page 89.

Opinion of Occam’s Financial Advisor (page 94)

Occam retained Jefferies & Company, Inc., which we refer to in this proxy statement/prospectus as Jefferies, to act as its financial advisor in connection with the merger transaction and to render to the Occam board an opinion as to the fairness of the consideration to be received by the holders of Occam common stock pursuant to the merger agreement. At the meeting of the Occam board on September 15, 2010, Jefferies rendered its opinion to the Occam board to the effect that, as of that date, and based upon and subject to the various considerations set forth in its opinion, the consideration to be received by holders of Occam common stock pursuant to the merger agreement was fair, from a financial point of view, to such holders.

Jefferies’ opinion sets forth, among other things, the assumptions made, procedures followed, matters considered and limitations on the scope of the review undertaken by Jefferies in rendering its opinion. Jefferies’ opinion was directed to the Occam board and addresses only the fairness, from a financial point of view and as of the date of the opinion, of the consideration to be received by holders of Occam common stock. It does not address any other aspects of the merger transaction and does not constitute a recommendation as to how any holder of Occam common stock should vote on the merger transaction or any matter related thereto.

The full text of the written opinion of Jefferies is attached to this proxy statement/prospectus as Annex B. Occam encourages its stockholders to read Jefferies’ opinion carefully and in its entirety.

Interests of Certain Persons in the Merger (page 105)

Occam’s executive officers and directors have financial interests in the merger transaction that are different from, or in addition to, their interests as Occam stockholders generally. The independent members of the Occam board were aware of and considered these interests, among other matters, in evaluating the merger agreement, and in recommending that the Occam stockholders adopt the merger agreement.

Each of Occam’s executive officers are parties to change in control severance agreements with Occam, which provide severance and other benefits in the case of qualifying terminations of employment following a change in control, including completion of the merger transaction that may result in the receipt by such executive officers of cash severance payments and other benefits with a total value of approximately $1,413,987 (collectively, not individually, and excluding the value of any accelerated vesting of stock awards) and the acceleration of stock awards held by those officers.

In addition, for Occam’s executive officers and non-employee directors, the completion of the merger transaction will result in, among other things, the conversion of vested stock options or restricted stock units into the right to receive the cash-out consideration less any applicable per share exercise price, the accelerated vesting and conversion of restricted stock into the right to receive merger consideration and the conversion of outstanding but unvested Occam stock options and restricted stock units into stock options and restricted stock units of Calix, subject to the compensatory award exchange ratio and which will remain subject to the vesting terms specified in the applicable award agreement. Occam’s officers and directors also have rights to indemnification and directors’ and officers’ liability insurance that will survive completion of the merger transaction.

For further information, including a discussion of the approximate value of the potential benefits that could be received by the executive officers and the directors of Occam upon completion of the merger transaction, please see “Proposal One—The Merger—Interests of Certain Persons in the Merger” beginning on page 105.

Outstanding Stock Entitled to Vote held by Certain Stockholders and the Vote Required to Adopt the Merger Agreement

As of September 25, 2010, all directors and executive officers of Occam, together with their affiliates, beneficially owned approximately 27% of the shares of Occam common stock. The affirmative vote of the holders of a majority of the shares of Occam common stock issued and outstanding is required for approval of the merger proposal.

Certain stockholders of Occam who collectively held approximately 27% of Occam’s common stock as of September 15, 2010 have entered into a support agreement pursuant to which Occam stockholders have agreed to vote their shares of Occam common stock in favor of the adoption of the merger agreement and have also agreed to certain limitations on the ability to transfer their Occam shares and to exercise other stockholder rights. This support agreement is discussed in greater detail in the section entitled “Support Agreement” in this proxy statement/prospectus.

Regulatory Approvals Required for the Merger (page 108)

Calix and Occam have agreed to use their reasonable best efforts to obtain all governmental and regulatory approvals required to complete the transactions contemplated by the merger agreement. These approvals include approval under the Hart-Scott-Rodino Act, or the HSR Act. Under the HSR Act, and the rules promulgated by the Federal Trade Commission, or the FTC, the merger transaction may not be completed until (1) certain information and materials are furnished to the Department of Justice, or the DOJ, and the FTC and (2) the applicable waiting period under the HSR Act is terminated or expires. Calix and Occam filed the required HSR notification and report forms with the FTC on September 27, 2010. Calix pulled and re-filed its HSR notification and report form on October 27, 2010, restarting the waiting period. If the DOJ or the FTC issues a Request for Additional Information and Documentary Material prior to the expiration of the waiting period, the parties must observe a second 30-day waiting period, which would begin to run only after both parties have substantially complied with the request for information, unless the waiting period is terminated earlier or extended with the consent of the parties.

Calix and Occam also intend to make all required filings under the Securities Act of 1933, as amended, or the Securities Act, and the Securities Exchange Act of 1934, as amended, or the Exchange Act, relating to the merger transaction, and obtain all other approvals and consents which may be necessary to give effect to the merger transaction.

Appraisal Rights (page 109)

Under the Delaware General Corporation Law, referred to as the DGCL, Occam stockholders who do not vote for the adoption of the merger agreement have the right to seek appraisal of the fair value of their shares as determined by the Delaware Court of Chancery if the first-step merger is completed, but only if they comply with all requirements of the DGCL, which are summarized in this proxy statement/prospectus. This appraisal amount could be more than, the same as, or less than the amount an Occam stockholder would be entitled to receive under the merger agreement. Any Occam stockholder intending to exercise appraisal rights, among other things, must submit a written demand for appraisal to Occam prior to the vote on the adoption of the merger agreement and must not vote or otherwise submit a proxy in favor of adoption of the merger agreement . Failure to follow exactly the procedures specified under the DGCL will result in the loss of appraisal rights. Because of the complexity of the DGCL relating to appraisal rights, if you are considering exercising your appraisal right, we encourage you to seek the advice of your own legal counsel.

NYSE Listing of Calix Common Stock (page 115)

Calix’s common shares currently trade on the NYSE under the stock symbol “CALX.” It is a condition to completion of the merger transaction that the Calix common shares to be issued by Calix to Occam stockholders in connection with the merger transaction be approved for listing on the New York Stock Exchange, or NYSE, subject to official notice of issuance. Calix has agreed to use all reasonable best efforts to cause the Calix common shares issuable in connection with the merger transaction, including those shares to be reserved for issuance upon the exercise or conversion of equity awards described above, to be authorized for listing on the NYSE and expects to obtain the NYSE’s approval to list such shares prior to completion of the merger transaction, subject to official notice of issuance.

Delisting and Deregistration of Occam Common Stock (page 115)

Shares of Occam common stock currently trade on the NASDAQ Global Market under the stock symbol “OCNW.” Upon completion of the merger transaction, all shares of Occam common stock will cease to be listed for trading on the NASDAQ Global Market and will be deregistered under the Exchange Act.

Conditions to the Merger (page 126)

The obligations of each of Occam, Calix and Ocean Sub I to consummate the first-step merger are subject to the satisfaction of the following conditions:

In addition, the obligations of Occam to consummate the first-step merger are subject to the satisfaction of the following conditions:

The obligation of Calix, Ocean Sub I, and Ocean Sub II, to complete the merger transaction is subject to the following conditions in addition to those described above:

Expected Timing of the Merger (page 109)

Calix and Occam currently expect to complete the merger in the fourth quarter of 2010 or the first quarter of 2011, subject to the receipt of required stockholder and regulatory approvals and the satisfaction or waiver of the other conditions to completion of the merger transaction. Because many of the conditions to completion of the merger transaction are beyond the control of Calix and Occam, the exact timing for completion of the merger transaction cannot be predicted with any amount of certainty.

No Solicitation of Offers by Occam (page 124)

The merger agreement contains detailed provisions that restrict Occam, its subsidiaries and their respective representatives from soliciting, initiating or knowingly encouraging, or taking other actions intended to facilitate, the submission of any other acquisition proposal. The merger agreement also contains restrictions on Occam, its subsidiaries and their respective representatives from participating in any discussions or negotiations regarding any other acquisition proposal. The merger agreement does not, however, prohibit the Occam board from considering and recommending to Occam stockholders an alternative transaction with a third party if specified conditions are met, including, in certain circumstances, the payment of a termination fee required by the merger agreement.

Termination of the Merger Agreement (page 128)

The merger agreement may be terminated at any time prior to the completion of the first-step merger by mutual consent of Occam and Calix. The merger agreement may also be terminated, subject to certain conditions, by either Occam or Calix if:

provided, with the exception of the circumstances described in the second bullet in the above list, no party may terminate the merger agreement for any of the circumstances stated above if such party’s breach of the merger agreement resulted in the occurrence of any circumstances.

Calix may terminate the merger agreement, subject to certain conditions, if:

Occam may terminate the merger agreement, subject to certain conditions, if:

Termination Fees and Expenses (page 129)

Occam has agreed to pay Calix a termination fee of $5,200,000 if the merger agreement is terminated:

Calix has agreed to pay Occam a termination fee of $5,000,000 if the merger agreement is terminated:

Calix has agreed to pay Occam a termination fee of $10,000,000 if the merger agreement is terminated:

Accounting Treatment (page 112)

In accordance with accounting principles generally accepted in the United States, or GAAP, Calix will account for the merger transaction using the purchase method of accounting for business combinations.

Material U.S. Federal Income Tax Consequences of the Merger Transaction (page 112)

The merger transaction has been structured to qualify as a reorganization within the meaning of Section 368(a) of the Code, and the consummation of the merger transaction is conditioned on the receipt by Occam of an opinion from its counsel to the effect that the merger transaction will so qualify. Assuming the merger transaction qualifies as a reorganization, for U.S. federal income tax purposes, U.S. stockholders of Occam will recognize gain (but not loss) with respect to their Occam common stock in an amount equal to the lesser of (i) any gain realized with respect to that stock or (ii) the amount of cash received with respect to that stock (other than any cash received instead of a fractional share of Calix common stock); and will recognize gain (or loss) to the extent any cash received instead of a fractional share of Calix common stock exceeds (or is less than) the basis of the fractional share.

The tax consequences of the merger transaction to each stockholder will depend on such stockholder’s own situation. Occam stockholders are urged to read the discussion in the section titled “Proposal One—The Merger—Material U.S. Federal Income Tax Consequences of the Merger Transaction” beginning on page 112 of this proxy statement/prospectus and to consult their tax advisors as to the U.S. federal income tax consequences of the merger transaction, as well as the effects of state, local and non-U.S. tax laws.

Management of Calix Following the Merger

Upon the effective time and subject to the review and approval of Calix’s board, one member of the Occam board who is not an employee of Occam, which individual shall be mutually and reasonably agreed to by Calix and Occam, will be appointed to the Calix board and will be nominated by the Calix board for election at Calix’s next annual meeting of stockholders. As of the date of this proxy statement/prospectus, no determination has been made as to the identity of the designee who will be appointed to the Calix board. There are currently no changes to Calix’s executive officers contemplated in connection with the merger transaction. Information about the Calix directors and executive officers who will continue to be Calix directors and executive officers after the effective time is set forth below in the section “Management Following the Merger—Management of Calix,” and information about members of the Occam board who are not employees of Occam, one of whom will be appointed to the Calix board after the effective time, is set forth below in the section “Management Following the Merger—Non-Employee Directors of Occam.”

Comparison of Rights of Calix Stockholders and Occam Stockholders (page 270)

The rights of Occam stockholders are currently governed by the Occam certificate of incorporation, the Occam bylaws and the DGCL. Occam stockholders, who will receive a portion of the merger consideration in Calix common shares, will become stockholders of Calix upon completion of the merger transaction. Thereafter, their rights will be governed by the Calix certificate of incorporation, the Calix bylaws and the DGCL. As a result, these Occam stockholders will have different rights once they become stockholders of Calix due to the differences in the governing documents of Calix and Occam. The key differences are described in the section titled “Comparison of Rights of Calix Stockholders and Occam Stockholders” beginning on page 270 of this proxy statement/prospectus.

SELECTED HISTORICAL AND UNAUDITED PRO FORMA

CONDENSED COMBINED FINANCIAL DATA

Selected Historical Financial Data of Calix

The following tables summarize Calix’s financial data. The statements of operations data for the nine months ended September 26, 2009 and September 25, 2010 and the balance sheet data as of September 25, 2010 are derived from Calix’s unaudited financial statements and related notes. The statements of operations data for the years ended December 31, 2007, 2008 and 2009 and the balance sheet data as of December 31, 2008 and 2009 are derived from Calix’s audited financial statements and related notes, which are included elsewhere in this proxy statement/prospectus. The statements of operations data for the years ended December 31, 2005 and 2006 and the balance sheet data as of December 31, 2005, 2006 and 2007 are derived from Calix’s audited financial statements and related notes, which are not included in this proxy statement/prospectus. Historical results are not indicative of the results that should be expected in the future.