Does fring even use SIP (it's compatible with SIP, but I assume the SIP connection is handled on frings servers which are not in dubai; hance allowing the connections to work)?
I find it hard to believe that the Nokia SIP stack is blocked but a different one works. I assume all SIP accounts are blocked?

Have you tried setting up a google talk account and something like this to dial SIP accounts: http://gtalk2voip.blogspot.com/2006/...nes-hello.html
That "should" work for the same reason fring works with SIP accounts