I have had a 2800Vg working with an Asterisk PBX successfully for about six years over a 'ropey' ADSL line with about 1M download as I'm right on the edge of my exchange area. I've just upgraded to FTTC with Plusnets 80/20 Fibre Extra service. I've only about a 100m of copper betwen the cabinet and my 2850 and yet my speed test give 60M down and 5M up although using the BT supplied modem I get 70M+ down and 15M+ up !!

But the major problem are the lines from one of my VoIP service providers. I have a VoIP line from Plusnet plus several lines from Sipgate Uk all terminating on the Asterisk PBX - they all use SIP protocol. They all show up as registered on the Asterisk (using both 'sip show peers' and 'sip show registry') However only the Plusnet line works - both in and out. When you dial one of the Sipgate numbers, no response is received and the call times out to busy tone / drops out depending if you are using a BT PSTN line or a mobile. The call never reaches the Asterisk as no response is seen on the Asterisk's CLI> log. All the same ports are open and pointed to the local IP of the Asterisk in exactly the same way as they were on the 2800Vn - Ports 4569, 5004, 5060-5082, 8000 to 20000.

All the extensions on the Asterisk can dial between each other without any problem and the Asterisk is part of a private network (connecting preserved old electro0mechanical telephone exchanges - CNet) that spans the World and other Asterisks can dial in no problem. However to dial out to connect to other Asterisks, we use an ENUM server which translates the dialled number into the IP address of the required Asterisk. When we contact the ENUM server, iot is unable to send its response back to my Asterisk.

Both these problems appear to be NAT/Firewall related and involve the relevant responses getting back to the Asterisk.

I can set the Sipgate numbers up on VoIP phones or Analogue Terminal Adapters direct and they work OK but not when the Asterisk is involved. I would have thought that opening the relevant ports and pointing them to the Asterisk's local IP address as worked fine on the 2800Vg would have been enough?

Anyone any ideas?

The router might be listening on port 5060 - make sure the 2850Vn's firmware is up to date and try this telnet command to disable the router's internal VoIP which should stop it listening on 5060:

voip sip misc -D 1
sys reboot (if it doesn't auto reboot after the first command)

Also, it may be that your 2800VG has SIP ALG enabled on it so try this telnet command if thing still don't work after disabling the router's VoIP:

sys sip_alg 1 (1 turns it on, 0 turns it off)

I was also told by a friend last week that he had had a problem for three weeks with several new 2850's he has on a network using VoIP and been eventually told by Draytek that VoIP is set to Off by default.

When I approached Draytek, I got the reply -
"By default the VoIP services are set to Off. You can telnet into the 2850 and use the sys sip_alg? (value is set to 0 or 1) command to enable/disable the service."

I've tried both your suggestion and theirs but still no joy.

Since the 2850 was fitted three weeks ago after being changed to FTTC, I've had no service on the VoIP PSTN lines that terminate on my Asterisk PBX. The Asterisk has worked fault free for over six years via a 2800Vg on ADSL2+ and now I expected it to work in a similar way with the change to the 2850Vn but that appears not to be the case.

Why have Draytek got the VoIP set to Off and no mention of it made anywhere in the manuals or websites?