Possible integration problem with Avaya SIP Enablement Services (SES) and Microsoft Exchange Unified Messaging
Over the past few months, I have encountered at least four instances of customers who are having problems integrating Avaya SES (SIP Enablement Services) with Microsoft Exchange Unified Messaging. All calls routed to Unified Messaging from Avaya SES 4.0.x or Avaya SES 5.0.x fail without ever connecting successfully, resulting in the following events which can be found in the application log of the Unified Messaging server:
Log Name: Application
Source: MSExchange Unified Messaging
Date: 12/22/2008 12:54:59 PM
Event ID: 1152
Task Category: UMCore
Level: Warning
User: N/A
Computer: umserver1.corp.fourthcoffee.com
Description:
The Unified Messaging server has received a SIP header that is not valid
from an incoming call with ID "d58f1efd-4201-4933-ab6b-06596f52fc58".
Header details follow: "System.FormatException: Original called number
information could not be obtained from the Diversion header:
""MSExchange" <sip:69001@corp.fourthcoffee.com>;index=1.2".”
Log Name: Application
Source: MSExchange Unified Messaging
Date: 12/22/2008 12:54:59 PM
Event ID: 1021
Task Category: UMCore
Level: Warning
User: N/A
Computer: umserver1.corp.fouthcoffee.com
Description:
The Unified Messaging server rejected an incoming call with the ID
"d58f1efd-4201-4933-ab6b-06596f52fc58". Reason: "Original called
number information could not be obtained from the Diversion header:
""MSExchange" <sip:69001@corp.fourthcoffee.com>;index=1.2"."
Log Name: Application
Source: Microsoft Exchange Speech Engine
Date: 12/22/2008 12:54:59 PM
Event ID: 32768
Task Category: Telephony Application Host
Level: Warning
User: N/A
Computer: umserver1.corp.fourthcoffee.com
Description:
The Telephony Manager declined a call with Call Id 'd58f1efd-4201-
4933-ab6b-06596f52fc58' for the following reason in component
telephony session: 'The application has requested that the call be
declined during media negotiation.'.
On an Exchange 2007 Unified Messaging server, the Unified Messaging service (UMService.exe) listens for inbound SIP connections on ports TCP/5060 and TLS/5061. Upon receiving an inbound connection request, the Unified Messaging service will redirect the calling device to either TCP/5065 or TLS/5066 where a waiting worker process (UMWorkerProcess.exe) will handle all signaling aspects of the call.
A successful call to Unified Messaging from a traditional PBX/IP Gateway should appear as follows:
While some gateways use the SIP Diversion header for recording historical routing information for a given call, Avaya uses the SIP History-Info header. Every routing or rerouting target throughout the history of a call is appended as an entry with an index value in the History-Info header. This means that when a voice mail call to the Unified Messaging service on port 5060 is redirected to the UM Worker Process listening on port 5065, three entries are added to the History-Info header by Avaya SES.
In Avaya SES 4.0.x, each routing or rerouting target is added as a separate line in the History-Info header for a given call. For example, a call placed to extension 27001 that is subsequently sent to voice mail will have a History-Info header similar to the following after being redirected (302 Moved Temporarily) to the UM Worker Process:
History-Info: <sip:27001@corp.fourthcoffee.com>;index=1
History-Info: "Microsoft UM" <sip:27001@corp.fourthcoffee.com?Reason=SIP%3Bcause%3D302%3Btext%3D%22Moved%20Temporarily%22&Reason=Redirection%3Bcause%3DCFI>;index=1.1
History-Info: "Microsoft UM" <sip:27001@corp.fourthcoffee.com>;index=1.2
In Avaya SES 5.0.x, each routing or rerouting target is added as a separate entry on the same line in the History-Info header for a given call. For example, the same voice mail call handled by Avaya SES 5.0.x will have a History-Info header similar to the following after being redirected to the UM Worker Process:
History-Info: <sip:27001@corp.fourthcoffee.com>;index=1,"Microsoft UM" <sip:27001@corp.fourthcoffee.com?Reason=SIP%3Bcause%3D302%3Btext%3D%22Moved%20Temporarily%22&Reason=Redirection%3Bcause%3DCFI>;index=1.1,"Microsoft UM" <sip:27001@corp.fourthcoffee.com>;index=1.2
While SIP Enablement Services appears to be RFC compliant in their presentation of History-Info information, the software also appends a display name value for each redirected History-Info entry, as highlighted below:
History-Info: "Microsoft UM" <sip:27001@corp.fourthcoffee.com>;index=1.2
We are currently investigating whether the inclusion of a display name value in History-Info could possibly be a contributing factor to the call transfer failures between Avaya SES and Unified Messaging. I have contacted Avaya regarding this issue, and their engineers have confirmed that SIP Enablement Services cannot be configured to omit the inclusion of display name values in History-Info.
Please contact me directly if you have any questions.
DaveH