Go back to your master socket and remove the extension faceplate; plug the router's line cord directly into the master and see if it works. Also try on a different line.

Using an analogue phone connected to voice port 1 of my 2820Vn (f/w 3.3.3_232201, no SIP accounts set-up, factory VoIP settings), I'm able to dial my mobile without the #0 prefix after I've entered the mobile number at either:

a) VoIP >> DialPlan Setup >> Digit Map Setup, or
b) VoIP >> PSTN Setup

Once the number has been dialled, I hear about 3s of slience, then two bleeps, then a further 4-5s of silence, a click and the mobile rings shortly afterwards. Does this work for you?

I've also tried '123' (the BT Speaking Clock) using both of the above methods, and that works fine too.

Incidentally, if you view the VoIP >> Status page during call attempts, do you see "Processing" / "Loop Through To PSTN" in the the Status area, and/or the dialled number listed under "Peer ID" in the Log area?

Thank D Malone, I'll let you know what I see.

Admin, I am not sure which is my master socket - they are all the same. I think it is only newer properties that have a master socket that you describe. I am trying to understand how your suggestion will help. I thought that broadband used my ADSL2 connection (which I get 6Mbs and no drop outs) and that the PSTN routing used the cable I connect between the phone socket on the router and BT socket (and I can make phone calls using directly connect phones). So, how can the switching in my router be affected by which socket in the house I use? Forgive my simplistic logic but what point am I missing and what might I discover by trying my router in all my other phone sockets?

I hope you don't mind my questioning.

Well, we know that loopthrough normally works, so something is different about your line; if your internal wiring wasn't good in the house, perhaps the line current is being reduced a bit and the router doesn't detect it enough...or the line won't carry the router-generated DTMF adequately... plugging into the primary socket (the first on in the series in your house) would exclude your onward wiring.. Or just try it at a friends house. You don't need ADSL on the line to test it.