One of my customers has an multipool Lync 2013 based in 4 countries.
We have been struggeling in different countries where we have trouble to see the presence. Typical error has been that we from the client only sees the Updateing status when searching for them.
From the error log on the client we saw this kind of error:
Start-Line: SIP/2.0 504 Server time-out
ms-diagnostics: 1039;reason="Failed to complete TLS
negotiation with a peer server";fqdn="
Based on this I figured out that this must be a certificate issue. So I changed the certificate on the frontend servers to include the FQDN on all the different frontends in the SITE.
And it works..........