Avaya SCN problems

[Darren]

Hello all, first post here. Not completely sure if this belongs in the firewall forum or the VPN forum, sorry if I posted in the wrong place. I am relatively new to fortigate (1 year experience) so I hope I' m not missing something completely obvious! We have two locations that are connected via BOVPN' s. The policies on both ends say to allow ALL services all the time. 192.168.15.0 network on one end and 192.168.3.0 network on the other. The 15.0 network is using a fortiwifi 90d and the 3.0 network is using a watchguard xtm 330. I purchased a fortigate 100d for the 3.0 network and installed it last weekend, everything was working great except for Avaya SCN to allow direct dialing between the two offices call servers. The call servers are on the 3.0 and 15.0 networks, and it works great from the fortiwifi to the watchguard, but as soon as I put in the 100d on the 3.0 network side, SCN stops communicating. ALL other traffic from 3.0 and 15.0 networks is working great. Any ideas why this would happen? Anyone with experience with Avaya SCN issues specifically? When you allow ALL services in the policy list, and the VPN is connected, is there any reason that some particular packets would be dropped by the 100d? I' m so confused... I have an appointment with a support engineer tonight but I am driving myself nuts with this issue... I had to put the watchguard back into production because of this. I honestly can not even imagine why it would be happening! Thanks in advance, Darren