MGC 7.5: Live Communication Server 2005 or Live Communication Server 2003 through a Cisco PIX firewall
Consider the following scenario.
You use a real-time communications (RTC) client to sign in to one of the following programs: Microsoft Office Live Communications Server 2003 or Microsoft Office Live Communications Server 2005 Additionally, the Live Communications Server computer is using a Cisco PIX firewall. In this scenario, the sign-in process may fail.
Additionally, you may receive the following error message:
"You have been signed out of SIP Communications Service because that service has been temporarily shutdown. Please try again later"
Note: This error message may vary depending on the client program that you are using. Additionally, you may experience intermittent presence issues. You may also experience issues when you try to send or to receive instant messaging (IM) messages or try to initiate a multipoint video conference.Some versions of Cisco PIX firewalls and virtual private network (VPN) solutions have built-in program-inspection functions for the Session Initiation Protocol (SIP). However, the built-in program-inspection functions are not fully compatible with real-time communications (RTC) client 5.0 or later versions of RTC client. RTC client includes Microsoft Windows Messenger 5.0, Windows Messenger 5.1, and Microsoft Office Communicator 2005.
This issue only occurs if you are not using Transport Layer Security (TLS) to help secure the communication between the client program and the server that is running Live Communications Server. In other words, the Cisco device cannot examine the traffic if the communication is encrypted.Disable the fixup SIP function on the Cisco PIX firewall or on the VPN device. To do this, run the following command: #no fixup protocol SIP 50607.5