We are in the process of converting over to Palo Alto firewalls at our remote locations from ASA firewalls. A few of our sites now are having some strange issues when attempting to make phone calls.We are a Cisco call manager shop.
Here is a basic setup of our network:
Remote Office <-Site to site VPN tunnell-> Main Office
Voice setup between those locations:
Analog lines (connected to router) - Remote Router - Remote Palo Alto <-Site to site VPN tunnell-> Main Office ASA firewall - Main Office Call-Manager
When someone at the remote location dials a external number, the phones SOMETIMES rings busy, even when the external phone number is not actually busy (tested and verified). The call will go through to the remote number but when they answer all they get is dead air. SOMETIMES the call goes through just fine. SOMETIMES when the call works and when the external number hangs up first the call stays active on the remote office's desk phone.
We've tried turning off ALG inside the SIP application, but when we test locally by setting up the calling search space to the remote office at a main office phone where we work, we still have problems.
