Microsoft ISA Firewall 2004

My network runs behind a MS ISA Firewall, how do I get external VOIP traffic to my internal asterisk server? Thanks in advance…

TBH. Buy another firewall, or do as many do, Bridge the ISA one with another one!!! . To date I have not heard of a successful voip deployment behind an ISA firewall. I know many that are set up as above though


I’ve had problems with ISA as well, I did as Ian suggested, and found another firewall solution. Couldn’t be bothered to find out what MS were doing to mess things up.

I am using ISA 2000 at my job and I can make and receive calls. I did not make any changes in the ISA server. I had to open a port in my watchguard firewall only.

What is behind it ? a Phone or the server ?

The problems are when the server is behind the firewall and the phones outside. I hve encounterd this with * and Mitel teleworkers.


I have first a Watchguard firewall and the ISA server is inside of our LAN. I can call out and in using FWD. Did you open the correct port on your firewall ?

These are customer sites not mine, I am confused why you are running a firewall in front of a firewall ? or are you not using the ISA as a firewall? the problem is when using ISA as a firewall. Its well documented that it has problems with all flavours of VOIP.