Hi guys, I have to M8L's and need to link them so Quadro A can call Quadro B via extension numbers. I have everything setup but I appears it does not work consistently.

Sometimes it does place the call and everything is clear, but most of the time the user on Quadro A calls the user on Quadro B and what happens is that user on Quadro B can't hear anything!, the user on Quadro A can hear the other end fine.... this also happens the other way around.

Sometimes we get the "Trying to connect" audio when dialing to the other Quadro.

The Quadros are being linked via their wan port obviously, they are sitting behind a 20Mbps internet connection (adsl) and both have dyndns hostnames (client does not have fixed public IP's)

The Quadros are behind Cisco SMB routers, on dmz (i know the hackers will try and hack this one) but I would also like to know what ports to open up on each rourter (I tried 5060 and the rtp range 6000-6099) but it only works when in dmz mode...

I would love to hear your comments on how to solve this issue... Thanks!