IP Phone Connects but other end has no sound

We have an IP 412 running v3.2 (53). I want to connect an IP phone (5602SW+ IP) from a remote office through a Watchguard x10e there and a Watchguard x750e here (via the VPN tunnel).

So, rather than risk going all the way down there and not being able to set it up, I decided to experiment. I set up the user / extension number and plugged the phone into our LAN. It worked perfectly. I then decided to try and replicate the phone connecting from a different IP address range, so I re-configured the user / extension number to a new IP address range and then configured one of the optional ports on the Watchguard x750e to the same address range. I then created an H323 policy, allowing all of the necessary ports. I then configured the phone itself and plugged it into the Watchguard's optional port. It booted up, but gave a "TPTP error: Timed out" message. However it then finished the boot and displayed the extension number and name. The phone gave a dial tone and I was able to pick up messages from the Voicemail Server. I then called another extension; the phone rang and I could hear the reply, but when I spoke, the other end couldn't hear a thing.

I've been trawling through everything to try and find a reason for this to happen, but without success. Has anybody got any ideas that might help?

 

[tlpeter]

You will need an IProute in the IPO pointing to the router.
try this

0.0.0.0
0.0.0.0
ipadress router
Lan 1 or 2(the one connected to the router)


BAZINGA!

I'm not insane, my mother had me tested!

 

[intrigrant]

The routing is simple but complex.
You call from a remote IP Phone through a VPN with a alog or digital station :
If they can hear you but you have dead silence : routing from IPO to phone
The other way around : routing from the phone to the IP Office
It is as simple as that BUT now the complex thing:
The actual routing part is the complex part of it. You really have to know how IP routing works and you have to be familiar with all the involved network components.
Ususally telecom engineers are not and if you are one of the many ( me included ) who have no indepth knowledge of all that : call a routing specialist.

If it ain't dutch it ain't much