THIRD FORBEARANCE TO LOAN AND SECURITY AGREEMENT

Exhibit 10.20.3

THIRD FORBEARANCE

TO

LOAN AND SECURITY AGREEMENT

This Third Forbearance to Loan and Security Agreement (this “Agreement”) is entered into this 31st day of August, 2005, by and among Silicon Valley Bank (“Bank” or “Silicon”) and each of the following named corporations: ACT Teleconferencing Inc., ACT Teleconferencing Services, Inc., ACT Videoconferencing, Inc., ACT Proximity, Inc., and ACT Research, Inc. (collectively and jointly and severally, the “Borrowers” and separately, a “Borrower”), with ACT Teleconferencing, Inc., whose chief executive office is located at 1526 Cole Boulevard, Suite 300, Golden, CO 80401, acting as the Borrowers’ agent.

RECITALS

A. Bank and Borrowers have entered into that certain Loan and Security Agreement dated as of November 12, 2004 (as the same has been amended by the First Forbearance Agreement referred to below and as the same may from time to time be further amended, modified, supplemented or restated, the “Loan Agreement”). Bank has extended credit to Borrowers for the purposes permitted in the Loan Agreement.

B. Bank and Borrowers entered into that certain Forbearance and Amendment to Loan and Security Agreement dated as of May 31, 2005 (the “First Forbearance Agreement”) and that certain Second Forbearance, Consent and Amendment to Loan and Security Agreement dated as of July 31, 2005 (the “Second Forbearance Agreement”), pursuant to which Bank agreed to forbear from exercising its rights and remedies against Borrowers, relating to certain events of default that had occurred under the Loan Agreement, through and including 08/31/05 on the terms and conditions set forth therein, and Bank agreed to amend certain provisions of the Loan Agreement, but only to the extent, in accordance with the terms, subject to the conditions and in reliance upon the representations and warranties set forth therein.

C. Borrowers entered into certain agreements with Dolphin Direct Equity Partners, LP, a Delaware limited partnership (“Dolphin”), providing for the sales of up to $16,000,000 of preferred stock of ACT Teleconferencing, Inc. (which will result in a change of control of Borrowers in excess of 20%) in two tranches, with the first in the amount of $8,000,000 which has been completed and the second in the remaining amount to be completed through a public rights offering to existing shareholders of ACT Teleconferencing, Inc., with Dolphin funding any shortfall. Pending shareholder approval of the first tranche. Dolphin loaned Borrowers up to $1,500,000 (the “Bridge Loan”) secured by a junior lien on Borrowers’ assets and subordinated to Bank (collectively, the “Transaction”). In connection with the Transaction, Borrowers used proceeds of the first tranche to repay the Bridge Loan and $5,000,000 to repay a portion of the then existing Subordinated Debt and the proceeds of the second tranche will be used to repay the remaining existing Subordinated Debt.

D. Borrowers again acknowledge that events of default occurred under the Loan Agreement (collectively, the “Existing Defaults”) and that Borrowers continue to be in default of the Loan Agreement as a result of Borrowers’ previous failure to comply with Section 5.3 (Schedule Section 6, subsections 5, 6 and 8) and Section 5.1 (Schedule Section 5) of the Loan Agreement.

E. Borrowers have requested that Bank continue to forbear from exercising its rights and remedies against Borrowers through and including 10/31/05 to allow Borrowers time to complete the second tranche of the Transaction or otherwise raise additional equity, refinance existing subordinated debt, continue restructuring, and implement their strategic plan. Although Bank is under no obligation to do so, Bank is willing to continue to forbear from exercising its rights and remedies against Borrowers through and including 10/31/05 on the terms and

conditions set forth in this Agreement, so long as Borrowers comply with the terms, covenants and conditions set forth in this Agreement in a timely manner.

AGREEMENT

Now, THEREFORE, in consideration of the foregoing recitals and other good and valuable consideration, the receipt and adequacy of which is hereby acknowledged, and intending to be legally bound, the parties hereto agree as follows:

1. Definitions. Capitalized terms used but not defined in this Agreement shall have the meanings given to them in the Loan Agreement.

2. Continued Forbearance.

2.1 Third Forbearance Period. So long as no Event of Default, other than the Existing Defaults, occurs, subject to the terms and conditions set forth herein, Bank shall continue to forbear from filing any legal action or instituting or enforcing any rights and remedies it may have against Borrowers through and including 10/31/05 (the “Third Forbearance Period”). Except as expressly provided herein, this Agreement does not constitute a waiver or release by Bank of any Existing Defaults or of any Obligations or of any Event of Default which may arise in the future after the date of execution of this Agreement. If Borrowers do not comply with the terms of this Agreement, Bank shall have no further obligations under this Agreement and shall be permitted to exercise at such time any rights and remedies against Borrowers as it deems appropriate in its sole and absolute discretion. Borrowers understand that Bank has made no commitment and is under no obligation whatsoever to grant any waiver or additional extensions of time at the end of the Third Forbearance Period.

2.2 Forbearance Terms. Repayment and performance of all obligations of Borrowers to Bank under the Loan Agreement and this Agreement shall be and shall continue to be secured by the Collateral. The terms of the First Forbearance Agreement and the Second Forbearance Agreement shall continue to apply except as set forth herein.

3. Limitation of Agreement.

3.1 The Agreement is effective for the purposes set forth herein and shall be limited precisely as written and shall not be deemed to (a) be a consent to any amendment, waiver or modification of any other term or condition of any Loan Document, or (b) otherwise prejudice any right or remedy which Bank may now have or may have in the future under or in connection with any Loan Document.

3.2 This Agreement shall be construed in connection with and as part of the Loan Documents and all terms, conditions, representations, warranties, covenants and agreements set forth in the Loan Documents are hereby ratified and confirmed and shall remain in full force and effect.

4. Representations and Warranties. To induce Bank to enter into this Agreement, each Borrower hereby represents and warrants to Bank as follows:

4.1 Immediately after giving effect to this Agreement (a) the representations and warranties contained in the Loan Documents are true, accurate and complete in all material respects as of the date hereof (except to the extent such representations and warranties relate to an earlier date, in which case they are true and correct as of such date), and (b) no Event of Default other than the Existing Defaults has occurred and is continuing;

2

4.2 Borrower has the corporate power and authority to execute and deliver this Agreement and to perform its obligations under the Loan Agreement;

4.3 The certificate of incorporation, bylaws and other organizational documents of Borrower delivered to Bank on November 12, 2004 remain true, accurate and complete and have not been amended, supplemented or restated and are and continue to be in full force and effect;

4.4 The execution and delivery by Borrower of this Agreement and the performance by Borrower of its obligations under the Loan Agreement, have been duly authorized by all necessary corporate action on the part of Borrower;

4.5 The execution and delivery by Borrower of this Agreement and the performance by Borrower of its obligations under the Loan Agreement, do not and will not contravene (a) any law or regulation binding on or affecting Borrower, (b) the certificate of incorporation or bylaws of Borrower, (c) any order, judgment or decree of any court or other governmental or public body or authority, or subdivision thereof, binding on Borrower, or (d) any contractual restriction with a Person binding on Borrower;

4.6 The execution and delivery by Borrower of this Agreement and the performance by Borrower of its obligations under the Loan Agreement, do not require any order, consent, approval, license, authorization or validation of, or filing, recording or registration with, or exemption by any governmental or public body or authority, or subdivision thereof, binding on either Borrower, except as already has been obtained or made; and

4.7 This Agreement has been duly executed and delivered by Borrower and is the binding obligation of Borrower, enforceable against Borrower in accordance with its terms, except as such enforceability may be limited by bankruptcy, insolvency, reorganization, liquidation, moratorium or other similar laws of general application and equitable principles relating to or affecting creditors’ rights.

5. Prior Agreement. Except as expressly provided for in this Agreement, the Loan Documents are hereby ratified and reaffirmed and shall remain in full force and effect. This Agreement is not a novation and the terms and conditions of this Agreement shall be in addition to and supplemental to all terms and conditions set forth in the Loan Documents. Nothing in this Agreement shall constitute a satisfaction of any of the Obligations. In the event of any conflict or inconsistency between this Agreement and the terms of such documents, the terms of this Agreement shall be controlling, but such document shall not otherwise be affected or the rights therein impaired.

6. Release by Borrowers.