said by know2much:I am surprise no one has replied, the reason is probably that BT territory runs 6 hours ahead of Eastern Time.
What I can tell from Mexico is that Telmex has apparently begun putting some DSL services behind some sort of firewall. You can access the internet just fine, but you can not run any server or services from these DSL lines.
FWD on these lines will work only if you enable SIP proxy, this is required even when you get a public IP address, and even if you do not run behind NAT, as this is the only way to open ports on the firewall.
Blocking ALL inbound ports is rather strange...usually it's just ports likely to be abused by hackers or servers. 
Of course, most "regular" VoIP services (Vonage, etc.) use SIP proxies by default to reduce support issues and because the bulk of the traffic is to the PSTN (so there's no real advantage network-wise to using STUN), so what Telmex is doing isn't really going to reduce VoIP traffic.