OK, if you perform a TELNET from a PC (unless your phones offer this facility, what is the response? I would say something like:

TELNET 192.162.1.9 5060

It certainly looks like there is no internal Firewall rule that's is stopping LAN traffic flowing.

Can you tell me what is happening at the Phone level? What errors are you getting? Not Registered? One way traffic communications?

Code:

Connecting To 192.168.1.9...Could not open connection to the host, on port 5060: Connect failed

I have tried forwarding to the port to my PC as well. I've checked with http://www.canyouseeme.org/ and the port doesn't seem to be open. I have various other port forwarding rules setup and they are working, so it almost seems to be 5060 specific.

I have tried disabling both the call and data filter but that didn't help.

OK, two further things.

1. Is 192.168.1.9 happy to receive data from other devices? It does not have a firewall of its own?

2. Have you seen the below guide for PORT Forwarding on Drayteks.

http://www.draytek.co.uk/support/kb_vigor_portforwarding.html

I need to have a think about this. If you have disabled the filters then it can't be the draytek blocking the ports. Which means it something else regarding PORT Forwarding or the actual phone system. Maybe even something else that I have not even considered yet!

Yep, definitely no issue with the port forwarding setup. There is obviously nothing setup in the way of VoIP on the router, but is there anything that needs disabling to use an external device instead? I'm just wondering if the Draytek has reserved 5060.

I know that 192.168.1.9 is happy to receive from other devices because we also have some other phones setup (wi-fi phones) which required port forwarding to 192.168.1.9, and these are working. It seems that 5060 is the issue...

As far as my memory serves in terms of our setup, each device needs its own separate PORT. In our office, we have four phones with the ports setup as 5060, 5062, 5064 and 5066 respectively.

Maybe the issue is that something is already using 5060.

Have you tried a NETSTAT on 192.168.1.9 to see if anything is connected on that PORT already?

I can't find anything using 5060 already. I'm going to email Draytek and see if they can shed any light. It does seem like port 5060 is reserved...