Issue with Microsoft OCS 2007 Speech Server
Symptom:
Using Dialogic® Diva® SIPcontrol™ Software with Microsoft® Office Communications Server 2007 (OCS) Speech Server, calls are reported to fail even though the configuration is correct. The error message states that ‘the requested RTP port is unreachable’.
Reason for the issue:
This is a known issue with OCS Speech Server that occurs when it tries to open the RTP port too early during the call establishment phase and receives an ICMP 'port unreachable' packet back.
This issue does not appear in all installations because the network may introduce enough delay so that the first RTP packets arrive when the call is already in the correct state.
Workaround:
When OCS Speech Server and Diva SIPcontrol Software are installed on different machines, a possible workaround is to prevent ICMP packets from reaching the OCS Speech Server machine using the Windows® firewall.
When both OCS Speech Server and Diva SIPcontrol Software are on the same machine, the principle for possible workarounds is the same: filter out the ICMP packets:
1. If the machine has two NICs, assign them separately to OCS Speech Server and Diva SIPcontrol Software; enable the Windows® firewall to filter out ICMP traffic.
2. If the machine has only one NIC, give it two IP addresses and assign the addresses to OCS Speech Server and Diva SIPcontrol Software respectively. Enable a firewall to filter out ICMP traffic.
3. Use a third-party firewall that can filter ICMP traffic on the loopback interface.
Product List
Dialogic® Diva® SIPcontrol™ Software.
First published: 24-Oct-2008
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