If the firewall does not have hardware accelerated encryption, a VPN is a very CPU intensive operation for a firewall/router. You don't say what model of sonicwall it is but it seems likely that it can't handle the load. VPNs on firewalls doing voice is a bad mix unless you're willing to spend good money on a decent firewall.
It's probably not exhausting its NAT translation pool or memory since there shouldn't be any additional NAT activity if you're using a VPN but if you have a way to check, that would also be worth a look. Another possibility is DNS. If you've changed something in your network topology when you moved Exchange, then perhaps one of the DNS servers is failing to resolve the VOIP provider causing intermittent registration failures. One question though; why are you doing Exchange over a VPN? Exchange communication is secured to the client (Outlook) via SSL certificates, there is no VPN needed. Double check with an Exchange expert (I'm not one) but I believe encrypted communication is mandatory on all Microsoft products these days. John --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
