I have a Vigor 2820 unit (not voip version) which works superbly. I also have a simple VOIP adaptor which I can plug into pretty much any RJ45 socket and have working phone line. Great.

The only problem is that they are not playing nicely together. When I plug the voice adaptor (actually a Thomson Speedtouch ADSL modem reflashed), it manages to register with the SIP provider (coms.com) and for a SHORT time after that, it will accept incoming calls. After about 5 minutes however if someone calls the number they are diverted to voice mail as "called number not available".

It **seems** to me (un-initiated) that when the adaptor registers, it is somehow able to leave a port open for a short time so when a call comes in, the Vigor2820 is able to let the adaptor know it has a call due.

THEN for some reason, it no longer lets inbound call signalling take place.

I am HOPING it is just a case of opening port 5060 - but I am then asked what internal ip address to allow access to the port - and if this is unplugged and another VOIP phone / adaptor is plugged in, I don't really want to have to go back and re-configure 5060 to a different internal address.

At home - with a really "cheap and dirty router", and number of different types and make of VOIP gear just "works" when plugged in. No port opening nothing.

The Vigor is a truly first rate router - but despite hours of googling (and looking through forums like this), I cannot find a simple way to make VOIP adaptors which "just work" on almost any other network - work when plugged into the Vigor.

I know there are 2820 VOIP tutorials but these all SEEM to assume I am using the 2820V unit. I am not - I am using external devices.

Please can someone guide me as to how I can solve whatever is stopping the VOIP adaptor working? (it also failed when I tried a Linksys SPA941 too - same problem).

Many thanks

Kind Regards

Mark

I know it's a while since you posted but I since no-one has replied I'll try and help if I can.
I've just got a pair of 2820's to setup a VPN between sites and whilst they aren't using voip, I do use voip at home albeit not with a 2820.
Ok enough of the background...
I'm pretty sure you're right in your deduction that the port isn't remaining open, so the incoming call can't be routed to the ATA
do you have UPnP enabled on the 2820 ( page 126 in the manual ) ? if not then try enabling it ( cheap and dirty routers tend to have it enabled )
does your ATA use STUN or does your voip provider have an outbound proxy for NAT traversal ?

Thank you for the reply!

I will go and see what the setting is - you may very well be right about the UPNP being set to disabled.

As for the SIP, it is a company called coms.com and although they have suggested I try to allow access to a range of their IP addresses, usually it is a really simple STUN system. At home - friends houses - almost anywhere else - I just plug the adaptor in and within a few seconds I have dialtone and can make/receive calls. Really nice and simple.

I suspect in fairness it is simply the "over-secure by default" setting on the 2820 which is causing the problem - that combined with me not being too technical.

Thanks so much for the thought on UPNP - I will make sure it is enabled and see if that makes a difference. Either way I will let you know back on here.

Thank you again for taking the time to help.

Kind regards
Mark

candl wrote: I know it's a while since you posted but I since no-one has replied I'll try and help if I can.
I've just got a pair of 2820's to setup a VPN between sites and whilst they aren't using voip, I do use voip at home albeit not with a 2820.
Ok enough of the background...
I'm pretty sure you're right in your deduction that the port isn't remaining open, so the incoming call can't be routed to the ATA
do you have UPnP enabled on the 2820 ( page 126 in the manual ) ? if not then try enabling it ( cheap and dirty routers tend to have it enabled )
does your ATA use STUN or does your voip provider have an outbound proxy for NAT traversal ?

I've had a look at the coms.com site and from their configuration guides it looks like they have an outbound proxy. Now the Draytek 2820 has a SIP ALG ( Application Layer Gateway ) and sometimes they can cause more trouble than they are worth.
You might changing the status of the SIP ALG.
You will need to telnet into the router and logon using your normal password.

Then using the command
sys sip_alg ?

Should return the current status.
And show you the commands to change the status

usage: sys sip_alg [value]
0 - disable SIP ALG
1 - enable SIP ALG

Hope that helps