I've been banging my head for days. Has someone got SJPhone 1.65 configured through a Cisco 837 ADSL router with the firewall feature set enabled?
I'm using draytel.org, but I've got the same issue with other providers such as Sipgate making it most likely to be a router config issue. Same SJPhone (SIP client) config works just fine on an "open" connection to the internet, so it's not a client config issue.
An example config to let SIP proxy connections behind a NAT'd Cisco 837 would be gold!