The Unified Messaging server has received an inbound call that has an invalid extension “%1” for UM dial plan “%2”. The call ID is “%3”.

This Warning event indicates that a diversion header is detected in the Session Initiation Protocol (SIP) request sent by the SIP peers (VoIP gateway or IP/PBX), but the extension used in the header does not match to the format expected for the requested Universal Resources Indicator (URI) type. A diversion header contains a URI that defines a communication resource. The diversion header also contains the reason for the diversion, such as no-answer when the dialed party did not answer, or user-busy when the line is busy. For example, “Diversion: <tel:10001>;reason=no-answer” is a diversion header with 10001 as the telephone extension. Without a valid extension in the header, the call will not be answered by the server. This event may be caused when the SIP peers send an invalid extension format in the diversion header.

To resolve this warning, do one or more of the following:

• Make sure that you have configured the IP/VoIP gateway correctly. For example, make sure that the format of the extension sent by the SIP peers matches the corresponding URI type as described in the following table:

  URI Type	Valid Format
  Telephone Extension (TelExtn)	All characters must be digits, and the number of digits must match the number of digits in the extensions defined in the dial plan. For example, 10001, 21008, or 50010 are valid extensions for a dial plan with a 5-digit extension.
  E.164 Number (E164)	The first character is always ‘+’. All subsequent characters must be digits. For example, +14255551234 and +4401234567890 are valid E.164 numbers.
  SIP Name (SipName)	A SipName URI resembles an SMTP address that is defined by RFC 821 specification. For example, someone@example.com is a valid SIP name.

  For more information for how to configure the IP/VoIP gateway, see How to Configure an IP/VoIP Gateway for Use with a Unified Messaging Server.

• Contact the vendors who support your VoIP gateway and IP/PBX hardware for help troubleshooting this issue.

• Run diagnostic tests on your VoIP Gateway or IP/PBX hardware to make sure that the devices are operational.

If you are not already doing so, consider running the tools that Microsoft Exchange offers to help administrators analyze and troubleshoot their Exchange environment. These tools can help you make sure that your configuration is in line with Microsoft best practices. They can also help you identify and resolve performance issues, improve mail flow, and better manage disaster recovery scenarios. Go to the Toolbox node of the Exchange Management Console to run these tools now. For more information about these tools, see Toolbox in the Exchange Server 2007 Help.