SUMMARY

This brief summary highlights selected information from this prospectus. It does not contain all of the information that is important to PLX stockholders. PLX stockholders are urged to read carefully the entire prospectus and the other documents referred to and incorporated by reference in this prospectus to fully understand the offer and the merger transactions. In particular, stockholders of PLX should read the documents attached to this prospectus, including the merger agreement, which is attached as Annex A. For a guide as to where you can obtain more information on IDT, see “Additional Information—Where You Can Find Additional Information” beginning on page 109.

The Offer

We are proposing to acquire all of the outstanding shares of PLX common stock in exchange for shares of IDT common stock and cash. For each outstanding share of PLX common stock, we are offering to exchange (i) 0.525 of a share of IDT common stock and (ii) $3.50 in cash, in each case, subject to adjustment for stock splits, stock dividends and similar events, and without interest thereon and less applicable withholding taxes, through our wholly-owned subsidiary, Pinewood. We refer to this consideration, or any different consideration per share of PLX common stock that may be paid pursuant to the offer, as the “offer consideration.”

After completion of the offer, IDT will cause Pinewood to complete a merger with and into PLX, with PLX continuing as the surviving corporation, in which each outstanding share of PLX common stock (except for shares beneficially owned, directly or indirectly, by IDT, shares held in treasury by PLX and shares held by PLX stockholders who have properly preserved their appraisal rights, if any, under Delaware law) will be converted into the right to receive the same consideration paid in exchange for each share of PLX common stock in the offer, subject to appraisal rights to the extent applicable under Delaware law. We refer to this merger throughout this prospectus as the “merger.” If, after the completion of the offer, we beneficially own at least 90% of the outstanding shares of PLX common stock or if we exercise our option to purchase additional shares directly from PLX to reach the 90% threshold, we may effect the merger without the approval of PLX stockholders, as permitted under Delaware law, subject to appraisal rights to the extent applicable under Delaware law. If, on the other hand, after the completion of the offer, we beneficially own more than 50%, but less than 90%, of the outstanding shares of PLX common stock, a meeting of PLX stockholders or an action by written consent and the affirmative vote of at least a majority of the shares of PLX common stock outstanding on the record date for such meeting will be needed to complete the merger. If the conditions to the offer are satisfied, IDT will have sufficient votes to adopt the merger agreement without the need for any other PLX stockholders to vote in favor of such adoption, as well as the ability to take action by written consent to approve the merger.

We currently anticipate that, immediately thereafter, if certain conditions are met, PLX will merge with and into Pinewood LLC, our wholly-owned subsidiary, with Pinewood LLC continuing as the final surviving entity. We refer to this merger throughout this prospectus as the “LLC merger,” and we refer to the merger and the LLC merger together as the “merger transactions.”

The number of shares of IDT common stock issued to PLX stockholders in the offer and the merger will constitute approximately 14.1% of the outstanding common stock of the combined company after the merger, based upon the number of outstanding shares of IDT common stock and PLX common stock on November 7, 2012, disregarding stock options, and shares of common stock that may be issued by IDT or PLX pursuant to an employee stock plan.

Exchange of Shares of PLX Common Stock (Page 51)

Upon the terms and subject to the conditions of the offer, promptly after the expiration of the offer, we will accept shares of PLX common stock that are validly tendered and not properly withdrawn in exchange for shares

of IDT common stock and cash. Each share of PLX common stock validly tendered and not properly withdrawn prior to the expiration of the offer will be exchanged for 0.525 of a share of IDT common stock and $3.50 in cash, in each case, subject to adjustment for stock splits, stock dividends and similar events, and without interest thereon, less applicable withholding taxes.

Timing of the Offer (Page 52)

We commenced the offer on May 22, 2012, the date of distribution of the initial prospectus. The offer is scheduled to expire at the end of the day on December 10, 2012, at 12:00 midnight, New York City time, unless we extend the period of the offer. All references to the expiration of the offer mean the expiration of the offer, as extended.

Conditions of the Offer (Page 54)

The offer is subject to a number of conditions, and IDT will not be required to accept any tendered shares of PLX common stock for exchange if any of these conditions are not satisfied or, where permissible, waived as of the expiration of the offer. These conditions provide, among other things, that:

IDT has agreed with PLX in the merger agreement that it will not consummate the offer unless the conditions set forth in the first, second, third and fourth bullet points in the immediately preceding paragraph are satisfied, or are waived by PLX. The offer is not subject to any financing condition.

Extension, Termination and Amendment (Page 52)

In the event that the conditions to the offer have not been satisfied or, where permissible, waived, upon the initial expiration of the offer (or as such expiration of the offer may be extended), we are required to extend the

offer for successive periods of up to twenty (20) business days until the earlier of such time that all of the conditions to the offer have been satisfied or, where permissible, waived, or the merger agreement has been terminated in accordance with its terms. We are also required to extend the offer for any periods required by the SEC.

As of October 30, 2012, the required governmental approval under the HSR Act with respect to the merger had not been obtained. Pursuant to the terms of the merger agreement, if, as of October 30, 2012, all of the conditions to the offer had been satisfied or, where permissible, waived, other than obtaining the required governmental approval pursuant to the HSR Act or both obtaining the required governmental approval pursuant to the HSR Act and meeting the minimum tender condition, the offer could be extended for an additional three (3) month period until January 31, 2013 at the election of either IDT or PLX, solely to satisfy those conditions. At the end of October 2012, IDT and PLX elected to extend the offer until January 31, 2013, solely to satisfy such conditions. If, as of January 31, 2013, such conditions are still not satisfied, IDT then has the option, in its sole discretion, to extend the offer for an additional three (3) month period to April 30, 2013, solely to satisfy those conditions, provided that the offer may in no event be extended past April 30, 2013. If, at any expiration of the offer, all of the conditions to the offer have been satisfied or, where permissible, waived, we will accept for payment and promptly pay for shares of PLX common stock tendered and not properly withdrawn in the offer. During any extension, all shares of PLX common stock previously tendered and not properly withdrawn in the offer will remain deposited with the exchange agent for the offer, subject to your right to withdraw your shares of PLX common stock. If we exercise our right to use a subsequent offering period as described below, we will first consummate the exchange with respect to the shares validly tendered and not properly withdrawn in the initial offer period.

In the event the merger agreement is terminated in accordance with its terms prior to the acceptance of any shares of PLX common stock for exchange pursuant to the offer, we will promptly terminate the offer without accepting any shares that were previously tendered.

Subsequent Offering Period (Page 54)

We may elect to provide subsequent offering periods of up to twenty (20) business days after the acceptance of shares of PLX common stock in the offer in accordance with Rule 14d-11 under the Exchange Act if, as of the expiration of the offer, all of the conditions to the offer have been satisfied or, where permissible, waived, but the total number of shares of PLX common stock that have been validly tendered and not withdrawn pursuant to the offer, together with shares of PLX common stock then directly or indirectly owned by IDT, is less than 90% of the total number of shares of PLX common stock then outstanding. If we exercise our right to use a subsequent offering period, we will first consummate the exchange with respect to the shares validly tendered and not properly withdrawn in the initial offer period. You will not have the right to withdraw any shares of PLX common stock that you tender in the subsequent offering period. If we elect to provide a subsequent offering period, we will make a public announcement to that effect no later than 9:00 a.m. New York City time on the next business day after the previously scheduled expiration.

Procedure for Tendering Shares (Page 57)

For you to validly tender shares of PLX common stock pursuant to the offer that you hold in your own name or in “street name” through a broker, the enclosed letter of transmittal, properly completed and duly executed, along with any required signature guarantees, or an agent’s message in connection with a book-entry transfer, and any other required documents, must be transmitted to and received by Computershare, Inc., the exchange agent for the offer, or the “exchange agent,” at one of its addresses set forth on the back cover of this prospectus, and certificates for tendered shares of PLX common stock must be received by the exchange agent at one of its addresses or those shares of PLX common stock must be tendered pursuant to the procedures for book-entry

transfer set forth in “The Offer—Procedures for Tendering Shares” below, and a confirmation of receipt of the tender received, which confirmation we refer to below as a “book-entry confirmation,” in each case before the expiration of the offer.

The procedure for tendering shares held in your ESOP account differs from the general procedures for tendering shares which are discussed above. Information on how to tender all or a portion of the shares allocated to your ESOP account can be found under “The Offer—Procedure for Tendering ESOP Shares” beginning on page 57.

Guaranteed Delivery (Page 58)

If you wish to tender shares of PLX common stock pursuant to the offer and your certificates are not immediately available or you cannot deliver the certificates and all other required documents to the exchange agent prior to the expiration of the offer or cannot complete the procedure for book-entry transfer on a timely basis, your shares of PLX common stock may nevertheless be tendered, if you comply with the guaranteed delivery procedures as set forth in “The Offer—Guaranteed Delivery” beginning on page 58.

Withdrawal Rights (Page 59)

You may withdraw any shares of PLX common stock that you previously tendered into the offer at any time before the expiration of the offer by following the procedures described under “The Offer—Withdrawal Rights” on page 59, provided that you will not have the right to withdraw any shares of PLX common stock that you tender in a subsequent offering period as described under “The Offer—Subsequent Offering Period” beginning on page 54. The procedure for withdrawing instructions to tender the shares held in your ESOP account varies from the general withdrawal instructions provided above. Information on how to withdraw the instruction to the Trustee to tender the shares allocated to your ESOP account can be found under “The Offer—Procedure for Tendering ESOP Shares” beginning on page 57.

Effect of a Tender of Shares (Page 59)

By executing a letter of transmittal, you irrevocably appoint our designees as your attorneys-in-fact and proxies, each with full power of substitution, to the full extent of your rights with respect to your shares of PLX common stock tendered and accepted for exchange by us. That appointment is effective if and when, and only to the extent that, we accept the shares of PLX common stock for exchange pursuant to the offer.

We will determine questions as to the validity, form, eligibility including time of receipt, and acceptance for exchange of any tender of shares of PLX common stock, in our sole discretion, and our determination shall be final and binding. We reserve the absolute right to reject any and all tenders of shares of PLX common stock that we determine are not in proper form or the acceptance of or exchange for which may, in the opinion of our counsel, be unlawful.

Delivery of Shares of IDT Common Stock and Cash (Page 60)

Subject to the satisfaction (or, where permissible, waiver) of the conditions to the offer as of the expiration of the offer, we will accept for exchange shares of PLX common stock validly tendered and not properly withdrawn promptly after the expiration of the offer and will exchange such shares of PLX common stock for the offer consideration and cash in lieu of fractional shares for the tendered shares of PLX common stock. In all cases, the exchange of shares of PLX common stock tendered and accepted for exchange pursuant to the offer will be made only if the exchange agent timely receives:

Cash Instead of Fractional Shares of IDT Common Stock (Page 61)

We will not issue any fractional shares of IDT common stock pursuant to the offer or the merger. Rather, IDT will arrange for the exchange agent to make a cash payment in lieu of the fractional shares.

The Merger Transactions (Page 83)

The merger agreement provides that, following completion of the offer, Pinewood will be merged with and into PLX, with PLX continuing as the “surviving corporation.” In the event that IDT beneficially owns at least 90% of the outstanding shares of PLX common stock upon completion of the offer, the merger agreement provides that the parties will take all necessary and appropriate action to cause the merger to become effective as soon as practicable following completion of the offer, without a meeting of or an action of written consent by PLX stockholders, by effecting a “short-form” merger under Delaware law. If the minimum tender condition is met, we have the option, subject to certain limitations described herein, which we refer to as the “top-up option,” to purchase from PLX additional newly-issued shares of common stock that, when added to the number of shares already owned by IDT, will constitute one share more than 90% of the shares of PLX common stock then outstanding. If, after the completion of the offer, IDT beneficially owns more than 50%, but less than 90%, of the outstanding shares of PLX common stock and IDT’s exercise of the top-up option will not result in it owning one share more than 90% of the outstanding shares of PLX common stock, a meeting of PLX stockholders or an action by written consent in lieu of a meeting and the affirmative vote of at least a majority of the shares of PLX common stock outstanding on the record date for such meeting will be needed to complete the merger. If the conditions to the offer are satisfied, IDT will have sufficient votes to adopt the merger agreement without the need for any other PLX stockholders to vote in favor of such adoption, as well as the ability to take action by written consent to approve the merger. We currently anticipate that, immediately thereafter, if certain conditions are met, PLX will merge with and into Pinewood LLC, our wholly-owned subsidiary, with Pinewood LLC continuing as the final surviving entity.

Limited Solicitation of Acquisition Proposals (Page 88)

Go-Shop Period. The merger agreement provides that, during the period, or the “go-shop period,” beginning on the date of the merger agreement and continuing until 11:59 p.m. (California time) on May 30, 2012, PLX is permitted to, directly or indirectly:

After the go-shop period expires, starting from 12:00 a.m. (California time) on May 31, 2012, which we refer to as the “no-shop period start date,” the “no-shop” period will commence. Within 24 hours of the no-shop period start date, PLX must notify IDT in writing of the identity of each party that submitted a competing proposal prior to the no-shop period start date, and together with this notification, provide to IDT a copy of any competing proposal (or, in the event no such copy is available, a reasonably detailed description of the competing proposal) and any modifications to such competing proposal submitted by any party during the go-shop period. The terms “competing proposal” and “competing inquiry” are described under “The Merger Agreement—Covenants—Limited Solicitation of Acquisition Proposals” beginning on page 88.

Solicitation after the Go-Shop Period. From and after 12:00 a.m. (California time) on the no-shop period start date, PLX must and must cause each of its subsidiaries and representatives to cease and cause to be terminated any solicitation, encouragement, discussions or negotiations with any third party that may be ongoing with respect to a competing proposal or competing inquiry and request the return or destruction of any non-public information from such third party. From the no-shop period start date until the effective time of the merger or, if earlier, the termination of the merger agreement, PLX has agreed that it and its subsidiaries will not, directly or indirectly:

However, PLX may continue discussions and negotiations with any “excluded party” until the earlier of (i) June 15, 2012, the fifteenth (15^th) day after the no-shop period start date or (ii) such time as such excluded party ceases to be an excluded party for purposes of the merger agreement. The term “excluded party” is described under “The Merger Agreement—Covenants—Limited Solicitation of Acquisition Proposals” beginning on page 88. On May 31, 2012, after the termination of the go-shop period, PLX confirmed that it did not receive any superior proposals (as such term is described under “The Merger Agreement—Covenants—Limited Solicitation of Acquisition Proposals” beginning on page 88) during the go-shop period and that no qualifying excluded party would be permitted to engage in any subsequent negotiations.

If, at any time on or after the no-shop period start date and prior to the consummation of the offer, PLX receives a written, bona fide competing proposal that was not solicited in violation of the merger agreement (including from an excluded party) and PLX’s board of directors determines in good faith (after consultation with

its independent financial advisors and outside legal counsel) that such competing proposal constitutes or would reasonably be expected to lead to a superior proposal (as such term is described under “The Merger Agreement—Covenants—Limited Solicitation of Acquisition Proposals” beginning on page 88) as compared to the terms of the merger agreement, and that its failure to take any action would be reasonably likely to result in a breach of its fiduciary duties under applicable law, then PLX and its representatives may:

From and after the no-shop period start date, PLX must promptly notify IDT (within twenty-four hours) in the event that PLX, any of its subsidiaries or any of its representatives receives (i) any competing proposal or a competing inquiry, (ii) any request for non-public information relating to PLX or any of its subsidiaries, or requests for information in the ordinary course of business consistent with past practice and unrelated to a competing proposal or (iii) any competing inquiry or request for discussions or negotiations regarding any competing proposal. PLX must indicate the identity of such third parties and provide an copy (or, in the event no such copy is available, a reasonably detailed description) of such competing inquiry, competing proposal, indication or request to IDT, including any modifications thereto. Thereafter, PLX must keep IDT informed on a current basis of the status of any such competing inquiry or competing proposal, and any material developments, discussions and negotiations, including furnishing copies of any revised written proposals or offers relating thereto.

PLX Board of Directors’ Recommendation (Page 91)

Except as expressly permitted by the terms of the merger agreement, PLX has agreed in the merger agreement that neither its board of directors nor any committee of the board of directors will take, or resolve, agree or publicly propose to take, any of the following actions:

Despite the foregoing, the merger agreement provides that at any time before IDT’s acceptance of the offer:

PLX has agreed not to effect an adverse recommendation change or terminate the merger agreement, in each case, with respect to a superior proposal unless the following obligations are satisfied:

Termination of the Merger Agreement (Page 95)

The merger agreement may be terminated at any time prior to the effective time of the merger by mutual written agreement of IDT and PLX.

The merger agreement may be terminated prior to the effective time of the merger by either IDT or PLX by giving notice of termination to the non-terminating party, subject to certain conditions:

IDT may terminate the merger agreement at any time prior to Pinewood’s acceptance of the shares tendered and not withdrawn pursuant to the offer, subject to certain conditions:

PLX may terminate the merger agreement at any time prior to the consummation of the offer, subject to certain conditions:

Termination Fee (Page 96)

In the event of a termination of the merger agreement by either IDT or PLX under specified circumstances, including with respect to the acceptance of a superior proposal by PLX, PLX will be required to pay IDT a termination fee of $13.20 million, which fee will be $6.27 million if the merger agreement is terminated in connection with PLX’s entry into an alternative acquisition agreement with an excluded party, or if such termination of the merger agreement under the specified circumstances occurs prior to the no-shop period start date.

PLX Board of Directors (Page 82)

The merger agreement provides that, upon acceptance for exchange of shares of PLX common stock in the offer, we will be entitled to designate a number of directors of PLX, rounded up to the next whole number, equal to the product of the total number of directors on PLX’s board of directors (determined after giving effect to the election of additional directors by IDT) and the percentage of aggregate number of shares of PLX common stock beneficially owned by us bears to the total number of shares of PLX common stock outstanding. This would enable us to control the PLX board of directors after completion of the offer.

Material U.S. Federal Income Tax Consequences (Page 61)

If the LLC merger is not completed for any reason, the exchange of PLX shares for cash and IDT common stock in the offer and the conversion of PLX shares in the merger will be fully taxable to PLX stockholders, and each PLX stockholder will be required to recognize gain or loss with respect to each share of PLX common stock surrendered in the offer or converted in the merger in an amount equal to the difference between (i) the sum of any cash received (including cash received in lieu of a fractional share of IDT common stock) and the fair market value of IDT common stock received and (ii) the tax basis of the shares of PLX common stock surrendered in exchange therefor.

It is a condition to the LLC merger that PLX receive a tax opinion from its counsel to the effect that the offer, the merger and the LLC merger, taken together, will qualify as a reorganization within the meaning of section 368(a) of the Code. However, the receipt of such tax opinion is not a condition to the completion of the offer or the merger. Therefore, it is possible that the offer and the merger are completed but that the LLC merger is not. If the LLC merger is completed and assuming the correctness of such tax opinion, a PLX stockholder who receives cash and shares of IDT common stock will recognize gain (but not loss) equal to the lesser of (i) any cash received (other than cash received in lieu of a fractional share of IDT common stock) and (ii) the excess, if any, of (x) the sum of the cash received and the fair market value of the IDT common stock received over (y) such PLX stockholder’s tax basis in the shares of PLX common stock exchanged therefor. In addition, such PLX stockholder will recognize gain or loss attributable to cash received in lieu of a fractional share of IDT common stock. PLX stockholders should consult their tax advisors for a full understanding of all of the tax consequences of the offer, the merger and the LLC merger (if it occurs) to them.

The tender of stock allocated to an ESOP account in exchange for merger consideration is not a taxable event. However, an ESOP participant will be subject to tax on the value of the participant’s vested ESOP account at the time the participant elects a distribution unless the participant makes an eligible rollover to an individual retirement account or the tax-qualified retirement plan of an employer.

Appraisal Rights (Page 65)

Under Delaware law, you will not have any appraisal rights in connection with the offer. However, the merger is expected to entitle you to appraisal rights under Section 262 of the Delaware General Corporation Law, which we refer to as the “DGCL.” A copy of the appraisal rights provisions of the DGCL is attached as Annex C to this prospectus.

Source and Amount of Funds (Page 66)

Neither the offer nor the merger transactions are conditioned upon any financing arrangements. In order to provide the offer consideration and the merger consideration, prepay PLX’s bank indebtedness, and pay related fees and expenses, IDT currently expects to (i) use proceeds from the sale of shares of preferred stock of one of its wholly-owned subsidiaries to Bank of America, N.A., or “Bank of America,” pursuant to a master repurchase agreement IDT signed with Bank of America in June 2011, which we refer to as the “repurchase agreement,” and (ii) draw funds from $50 million of new financing arranged by IDT with J.P. Morgan Securities LLC and J.P. Morgan Chase Bank, N.A., collectively “J.P. Morgan,” in connection with the offer and the merger transactions, consisting of a $50 million revolving credit facility, or the “revolving credit facility.”

Under the repurchase agreement, IDT is obligated to make monthly “price differential” (as defined in the repurchase agreement) payments to Bank of America based on the outstanding purchase price of the purchased securities at a floating interest rate of LIBOR plus 2.125% which are calculated and accrue on a daily basis, and Bank of America is required to remit to IDT any dividends and other distributions that it receives on the purchased securities, unless an event of default with respect to IDT has occurred and is continuing under the repurchase agreement. Loans under the revolving credit facility are expected to bear interest, at IDT’s option, at a rate equal to either (a) the “ABR,” defined as the greatest of (i) J.P. Morgan’s prime rate, (ii) the federal funds effective rate plus 0.5% and (iii) the adjusted one-month LIBO rate plus 1.0%, plus the applicable margin, or (b) the adjusted LIBO rate plus the applicable margin. For purposes of the revolving credit facility, “applicable margin” means 2.5% in respect of loans bearing interest based upon the adjusted LIBO rate and 1.5% in respect of loans bearing interest based upon the ABR.

The sales of the preferred stock pursuant to the repurchase agreement, and the obligations of Bank of America to buy such shares of preferred stock, are subject to terms and conditions customary for transactions of this type, although the transactions contemplated by the repurchase agreement are not conditioned upon the completion of the offer or the merger in any way. IDT may only borrow amounts under the revolving credit facility if the offer is successful, all of the conditions to the offer are satisfied or, where permissible, amended or waived in a manner that is not material and adverse to J.P. Morgan, prior to January 31, 2013. Any amounts borrowed under the revolving credit facility may be used in connection with the offer and the merger as well as for general corporate purposes. The revolving credit facility would not be available if the merger agreement were terminated. If the conditions to the transactions pursuant to the repurchase agreement and the conditions to the revolving credit facility are not satisfied, IDT expects that its cash on hand and short-term investments will be sufficient to finance the cash portion of the offer consideration and the merger consideration and the ongoing working capital and other general corporate purposes of the combined company after the consummation of the merger.

IDT currently has no agreement, arrangement or understanding to repay or refinance the revolving credit facility or repurchase the preferred stock under the repurchase agreement after the merger has been completed, other than at the specified repurchase date, with respect to the repurchase agreement, or at the stated maturity, with respect to the revolving credit facility.

Regulatory Approvals (Page 69)

We and PLX have agreed pursuant to the merger agreement to use, and cause our respective subsidiaries to use, commercially reasonable efforts to take whatever actions are required to obtain necessary regulatory approvals with respect to the offer and the merger transactions. Other than clearance under the U.S. antitrust laws applicable to the offer and the merger transactions that are described below and that have already been obtained, the SEC declaring the effectiveness of the registration statement of which this prospectus is a part and the filing of certificates of merger under the DGCL with respect to the merger and the LLC merger, we do not believe that any additional governmental filings are required with respect to the offer and the merger transactions.

Under the HSR Act, and the related rules, the merger may not be completed until we and PLX notify and furnish information to the Federal Trade Commission and the Antitrust Division of the United States Department of Justice and specified waiting period requirements have been satisfied.

Accounting Treatment (Page 71)

In accordance with Accounting Standards Codification, or “ASC,” Topic 805, Business Combinations, or “ASC 805,” IDT will account for the transactions as a purchase business combination. Upon consummation of the transactions, IDT will record the acquisition at cost with cost consisting of the fair value of IDT common stock and stock options issued and the cash consideration issued. The total cost will be allocated based on the fair value of tangible and identifiable intangible assets acquired and liabilities assumed. The excess of cost over the fair value of net assets acquired will be recorded as goodwill.

Interests of Certain Persons in the Offer and the Merger (Page 72)

Certain PLX directors, officers and stockholders have interests in the offer and the merger that are different from, or are in addition to, those of other stockholders. These interests include:

In addition, all of the PLX directors and executive officers have entered into a tender and support agreement with IDT, pursuant to which those directors and executive officers will be required to tender and, except as described therein, not withdraw shares of PLX common stock owned by them. See “Other Agreements Related to the Transaction—Tender and Support Agreement” on page 98 of this prospectus.

The boards of directors of PLX and IDT were aware of these interests and considered them, among other matters, when they approved the offer, the merger and the merger agreement.

As of the date of this prospectus, IDT does not beneficially own any shares of PLX common stock.

Comparison of Rights of Holders of IDT Common Stock and PLX Common Stock (Page 103)

IDT and PLX are both organized under the laws of the state of Delaware. As a result of the offer and the merger, PLX’s stockholders will become stockholders of IDT, and rights as stockholders will be governed by IDT’s certificate of incorporation and bylaws. There are differences between the certificate of incorporation and bylaws of PLX, on the one hand, and the certificate of incorporation and bylaws of IDT, on the other hand.

The Companies

Integrated Device Technology, Inc.

6024 Silver Creek Valley Road

San Jose, California 95138

Telephone: (408) 284-8200

www.idt.com

Integrated Device Technology, Inc., is a Delaware corporation. We design, develop, manufacture and market a broad range of low-power, high-performance mixed signal semiconductor solutions for the advanced

communications, computing and consumer industries. Currently, we offer communications solutions for customers within the enterprise, data center and wireless markets. Our computing products are designed specifically for desktop, notebook, sub-notebook, storage and server applications, optimized gaming consoles, set-top boxes, digital TV and smart phones for consumer-based clients.

IDT’s common stock is currently quoted on NASDAQ (symbol: “IDTI”).

PLX Technology, Inc.

870 W. Maude Avenue

Sunnyvale, California 94085

Telephone: (408) 774-9060

www.PLXtech.com

PLX Technology, Inc., incorporated under the laws of Delaware, designs, develops, manufactures, and sells integrated circuits that perform critical system connectivity functions. These interconnect products are fundamental building blocks for standards-based electronic equipment. PLX markets its products to major customers that sell electronic systems in the enterprise, consumer, server, storage, communications, PC peripheral and embedded markets.

PLX’s common stock is currently quoted on NASDAQ (symbol: “PLXT”).

Comparative Per Share Market Price and Dividend Information (Page 20)

On April 27, 2012, the last trading day before IDT and PLX announced the offer, IDT common stock closed at $6.67 per share and PLX common stock closed at $4.06 per share. On November 8, 2012, the last trading day prior to the date of this prospectus for which this information was practicably available, IDT common stock closed at $5.73 per share and PLX common stock closed at $4.25 per share.

Neither IDT nor PLX has paid any dividends in the prior two fiscal years and IDT does not anticipate paying any cash dividends on its common stock in the foreseeable future.

Questions About the Offer and the Merger Transactions

If you have any questions about the offer or the merger transactions or if you need additional copies of this prospectus, you should contact our information agent:

INNISFREE M&A INCORPORATED

501 Madison Avenue, 20^th Floor

New York, NY 10022

Stockholders Call Toll-Free: (877) 456-3463

Banks and Brokers Call Collect: (212) 750-5833

SELECTED HISTORICAL FINANCIAL DATA

IDT Summary Selected Historical Consolidated Financial Data

The following table sets forth certain consolidated financial data of IDT. The selected consolidated statements of operations data for the years ended April 1, 2012, April 3, 2011, and March 28, 2010 and the selected consolidated balance sheet data as of April 1, 2012 and April 3, 2011 were derived from the consolidated financial statements included in IDT’s Annual Report on Form 10-K for the year ended April 1, 2012 which is incorporated by reference into this prospectus. The selected consolidated statements of operations data for the years ended March 29, 2009 and March 30, 2008 and the selected consolidated balance sheet data as of March 28, 2010, March 29, 2009, and March 30, 2008 are derived from IDT’s consolidated financial statements, which are not incorporated by reference into this prospectus. The consolidated financial data as of and for the six months ended September 30, 2012 and October 2, 2011 are derived from IDT’s unaudited consolidated condensed financial statements incorporated by reference into this prospectus. In IDT’s opinion, these unaudited consolidated condensed financial statements include all adjustments (consisting of normal recurring adjustments) necessary for a fair statement of IDT’s financial position and results of operations for these periods. You should read these financials together with IDT’s “Management Discussion and Analysis of Financial Condition and Results of Operations” and IDT’s historical consolidated financial statements and notes thereto. The historical results are not necessarily indicative of results to be expected in the future.

PLX Selected Historical Consolidated Financial Data

The following table sets forth certain consolidated financial data of PLX. The selected consolidated statements of operations data for the years ended December 31, 2011, 2010 and 2009 and the selected consolidated balance sheet data as of December 31, 2011 and 2010 were derived from the consolidated financial statements included in PLX’s Annual Report on Form 10-K for the year ended December 31, 2011 and PLX’s Current Report on Form 8-K filed on November 9, 2012, which are incorporated by reference into this prospectus. The selected statements of operations data set forth below for each of the years ended December 31, 2008 and 2007, and the selected consolidated balance sheet data as of December 31, 2009, 2008 and 2007 are derived from PLX’s audited consolidated financial statements, which are not incorporated by reference into this prospectus. PLX’s consolidated financial statement data set forth below as of and for the nine months ended September 30, 2012 and 2011 are derived from PLX’s unaudited financial statements included in its Quarterly Report on Form 10-Q for the quarter ended September 30, 2012, which is incorporated by reference into this prospectus. You should read these financials together with PLX’s “Management’s Discussion and Analysis of Financial Condition and Results of Operations” and PLX’s historical consolidated financial statements and notes thereto. The historical results been revised for adoption of Financial Accounting Standards Board, or “FASB,” Accounting Standards Update No. 2011-05, “Presentation of Comprehensive Income,” and FASB Accounting Standards Update No. 2011-12, “Deferral of the Effective Date for Amendments to the Presentation of Reclassifications of Items Out of Accumulated Other Comprehensive Income in Accounting Standards Update No. 2011-05.” The historical results are not necessarily indicative of results to be expected in the future.