VOTING AGREEMENT

Exhibit 4.2

VOTING AGREEMENT

     This Voting Agreement, dated as of October 18, 2006 (this “ Agreement ”), is by and among Vertical Communications, Inc., a Delaware corporation (“ Vertical ”), Vodavi Technology, Inc., a Delaware corporation (the “Company”), and LG-Nortel Co. Ltd (“ Stockholder ”).

W I T N E S S E T H

     WHEREAS, as of the date hereof, Stockholder owns beneficially the number of shares of common stock of the Company set forth opposite Stockholder’s name on Schedule I hereto (all shares so owned and which may hereafter be acquired by Stockholder prior to the termination of this Agreement, whether upon the exercise of options, conversion of convertible securities, exercise of warrants or by means of purchase, dividend, distribution or otherwise, being referred to herein with respect to Stockholder as the “ Stockholder Shares ”); and

     WHEREAS, contemporaneously with the execution and delivery of this Agreement, the Company is entering into an Agreement and Plan of Merger, dated as of the date hereof (as such agreement may hereafter be amended from time to time, the “ Merger Agreement ”), along with Vertical, and Vertical Acquisition Sub Inc., a Delaware corporation and a wholly owned subsidiary of Vertical (“ Sub ”), which provides for, upon the terms and subject to the conditions set forth therein, the merger of Sub with and into the Company (the “ Merger ”); and

     WHEREAS, pursuant to the Merger Agreement, the Company has agreed to call a special meeting of its stockholders for the purpose of (the “ Proposal ”); and

     WHEREAS, in consideration of Vertical entering into the Merger Agreement and incurring certain related fees and expenses relating to the Merger, Stockholder has agreed to enter into this Agreement; and

     WHEREAS, Vodavi is a party to this Agreement for the purpose of facilitating certain continuing relationships between Stockholder and Vertical following the Effective Time.

     NOW, THEREFORE, in consideration of the foregoing and the mutual covenants and agreements herein contained, and intending to be legally bound hereby, the Company, Vertical and Stockholder hereby agree as follows:

ARTICLE I.

VOTING OF SHARES; AND OTHER COVENANTS OF STOCKHOLDER AND VERTICAL

     SECTION 1.1. Voting of Shares . From the date hereof until termination of this Agreement pursuant to Section 3.2 hereof (the “ Term ”), at any meeting of the stockholders of the Company called to vote on the Proposal or at any adjournment or postponement thereof, and in any action by consent of the stockholders of the Company with respect to which approval of the Proposal is sought, Stockholder shall (A) appear at such meeting or otherwise cause its Stockholder Shares to be counted as present thereat for purposes of establishing a quorum and

(B) vote (or cause to be voted) its Stockholder Shares in favor of the Proposal and such other matters as may be necessary or advisable to consummate the transactions contemplated by the Merger Agreement.

     SECTION 1.2. No Inconsistent Arrangements . Except as contemplated by this Agreement, Stockholder shall not during the Term (i) grant any proxy, power-of-attorney or other authorization in or with respect to its Stockholder Shares which is inconsistent with the terms hereof, (ii) deposit its Stockholder Shares into a voting trust or enter into a voting agreement or arrangement with respect to its Stockholder Shares, (iii) sell, transfer, pledge or encumber, assign or otherwise dispose of or enforce or permit the execution of the provisions of any redemption, share purchase or sale, recapitalization or other agreement with the Company or enter into any contract, option or other arrangement or understanding with respect to the offer for sale, sale, transfer, pledge, encumbrance, assignment or other disposition of any of the Stockholder Shares except to a person who agrees in writing to be bound by the terms and conditions of this Agreement as a Stockholder or (iv) take any other action that would in any way restrict, limit or interfere with the performance of its obligations hereunder or the transactions contemplated hereby or by the Merger Agreement.

     SECTION 1.3. Disclosure . Stockholder hereby authorizes Vertical and/or the Company to publish and disclose in any filing with the SEC, including any proxy statement relating to the approval of the Merger Agreement by the Company’s stockholders (including all exhibits and schedules filed with the SEC), its identity and ownership of its Stockholder Shares and the nature of its commitments, arrangements and understandings under this Agreement.

     SECTION 1.4. Continuing Business Relationships . In consideration of Stockholder’s compliance with its obligations contained in Section 1.1, Vertical agrees that during the Term and continuing for a two-year period following the Term: (a) Vertical shall continue to support Stockholder’s product line consistent with the historic relationship between the Company and Stockholder; and (b) Vertical will distribute, on a non-exclusive basis, certain LG-Nortel products in fulfilling purchase orders for Nortel and supporting the LG-Nortel products sold by Nortel in North America on mutually acceptable terms; and (c) for the purpose of facilitating the transition following the Effective Time, prior to the Effective Time, Vertical shall enter into arrangements whereby Vodavi’s current chief executive officer and chief financial officer agree to cooperate with transitional services related to Stockholder’s relationship with the Company for a term of no less than nine months from the Effective Time.

ARTICLE II.

REPRESENTATIONS AND WARRANTIES OF STOCKHOLDER

     Stockholder hereby represents and warrants as follows:

     SECTION 2.1. Authority . Stockholder has all requisite power and authority to execute, deliver and perform this Agreement and to consummate the transactions contemplated hereby. The execution, delivery and performance of this Agreement and the consummation of the transactions contemplated hereby have been duly authorized by all necessary action on the part of Stockholder. This Agreement has been duly executed and delivered by or on behalf of

Stockholder and constitutes a legal, valid and binding obligation of Stockholder, enforceable against Stockholder in accordance with its terms, except as enforcement may be limited by bankruptcy, insolvency, moratorium or other similar laws and except that the availability of equitable remedies, including specific performance, is subject to the discretio