|   | 1.I      have reviewed this annual report on Form 10-K of Avistar      Communications Corporation; |
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|   | 2.Based      on my knowledge, this report does not contain any untrue statement of a      material fact or omit to state a material fact necessary to make the      statements made, in light of the circumstances under which such statements      were made, not misleading with respect to the period covered by this      annual report; |
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|   | 3.Based      on my knowledge, the financial statements, and other financial information      included in this report, fairly present in all material respects the      financial condition, results of operations and cash flows of the      registrant as of, and for, the periods presented in this      report; |
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|   | 4.The      registrant’s other certifying officer(s) and I are responsible for      establishing and maintaining disclosure controls and procedures (as      defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and      internal control over financial reporting (as defined in Exchange Act      Rules 13a-15(f) and 15d-15(f)) for the registrant and  have: |
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|   | a)      Designed such disclosure controls and procedures, or caused such      disclosure controls and procedures to be designed under our supervision,      to ensure that material information relating to the registrant, including      its consolidated subsidiaries, is made known to us by others within those      entities, particularly during the period in which this report is being      prepared; |
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|   | b)      Designed such internal control over financial reporting, or caused such      internal control over financial reporting to be designed under our      supervision, to provide reasonable assurance regarding the reliability of      financial reporting and the preparation of financial statements for      external purposes in accordance with generally accepted accounting      principles; |
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|   | c)      Evaluated the effectiveness of the registrant’s disclosure controls and      procedures and presented in this report our conclusions about the      effectiveness of the disclosure controls and procedures, as of the end of      the period covered by this report based on such evaluation;      and |
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|   | d)      Disclosed in this report any change in the registrant’s internal control      over financial reporting that occurred during the registrant’s most recent      fiscal quarter (the registrant’s fourth fiscal quarter in the case of an      annual report) that has materially affected, or is reasonably likely to      materially affect, the registrant’s internal control over financial      reporting; and |
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|   | 5.The      registrant’s other certifying officer(s) and I have disclosed, based      on our most recent evaluation of internal controls over financial      reporting, to the registrant’s auditors and the audit committee of the      registrant’s board of directors (or persons performing the equivalent      functions): |
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|   | a)      All significant deficiencies and material weaknesses in the design or      operation of internal control over financial reporting which are      reasonably likely to adversely affect the registrant’s ability to record,      process, summarize and report financial information;  and |
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|   | b)      Any fraud, whether or not material, that involves management or other      employees who have a significant role in the registrant’s internal control      over financial reporting. |
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| Date:      March 31, 2008     |   |   |
|------------------------------------|--------|--------|
| /s/      Simon B. Moss             |   |   |
| Simon      B. Moss                 |   |   |
| Chief      Executive Officer       |   |   |
| (Principal      Executive Officer) |   |   |