We have a Mitel ICP 3300 at Head Office. All handsets are 5330.
Branch Office #1 has a Site-to-Site VPN to Head Office
Branch Office #2 has a Site-to-Site VPN to Head Office.
The issue I am having, is if a user from Branch #1 calls a user at Branch #2 the phone will ring, when they pickup it is dead air. This is the same in both directions.
Here is what I'm wondering. Does the Handset in Branch #1 talk directly to the handset in Branch #2 or does everything pass through the ICP? Both Branches DO NOT have a route to each other, just to the subnet at Head Office.
I thought I read somewhere that when you make a call the ICP initiates then hands off the communication directly between the handsets. Which would explain the problem.
Anyone able to confirm my thoughts or offer some insight?
The call setup tells each phone what the other's IP address is and which port they are listening on.