Here are some steps for Troubleshooting OCS federation:
1. Verify DNS SRV records
Use the ResKit tool srvlookup to test your DNS SRV records. Use the command “srvlookup domain.com -v
The output should point to you SIP record (example: sip.domain.com)
2. OCS validation
Use the Validate Edge Server tool, on the Access Edge server, to locate any errors in the configuration
3. Verify certificate
Validate and verify the sip certificate on the Access Edge server. This must be a public and valid certificate for Federation to work. If you know your federation partner, you can exchange certificates, but this should only be done in test.
4. Verify connectivity
Test your firewall configuration by accessing port 5061. This can be done by telnet to your server from the Internet. (example: “telnet sip.domain.com 5061″) This should result in a blank screen (connection)
5. Contact your federation partner
Make sure that your federation partner has Open Federation, or that your domain is allowed to federate to them. This is probably the most common cause of problems
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