Today I have faced an issue with OCS 2007 R2 remote access not working and the client returns “Cannot Sign in because the server is temporary unavailable. If the problem persists, Contact your systems administrator”

Well I know this happens because of a problem with ports configured on the Edge.

Running a SIPSTACK trace on the Edge showed the following


Well as you see the listening port is 5061. Well that’s wrong because it should work on 443.

After double checking that the External Access port on the edge is set to 443, I went to the client and changed the External URL to, and guess what ? the client surely signed in.

So whether you are running manual or automatic login make sure you specify the port in the Server Address or in the SRV record and set it to 443.