Using 2 (or more) ATAs at one location

Question regarding using 2 (or more) ATAs at a single location.

I currently have 2 ATAs setup so I can have 4 different lines. Works fine most of the time. But every now and then we have an issue with inbound calls not ringing through. So I figured I should find out what is the "best practice" for this scenario.

Should the 2 ATAs be on the same subnet? Or cascaded (one plugged into the other)?

When forwarding ports through the ISP's (Comcast) firewall, I would usually pass 5004-65000. But what should I do in the case of 2 (or theoretically more) ATAs? Is it enough to just pass port 5060, 5061 (etc) to the specific ATA?

Anyone know the most stable way to configure this?

I wish I knew more about what all ports were doing what.

I hate to resurrect an old thread but I have the same question. Any information available about this?

Try 1 I hate this forum software!

If we could just delete posts

Try 2

You know, several months ago these "moderated posts" would have never showed up...

Try 3 that was moderated...

Ive replied 3 times but the forum software hates me.

Couple of idea's...

1. If your ISP will give you two IP's, get your modem into bridge mode (if its not a bridge only modem). Put a switch behind the modem, and put one of your ATA's on a public IP, or even behind a second router (and forward ports). If you have an RT31P2 this is a no brainer. The ATA on your LAN would have the Port forwarding done for it for that IP..

2. Find an older computer or embedded device and install pfSense (or Monowall) and install the siproxd package (sip proxy). This also entails putting modem in bridge mode if its not already... but no port forwarding. Voipo's servers see the proxy as your ATA's. The proxy forwards to the correct device. I use this here and at the office with multiple devices on each with no issues.

I use a few Obi110s and just made sure the X_UserAgentPort was unique per line (5060,5061,5062,5063) and I also set the RTP port ranges to be unique per line.

why not just setup some free pbx and have them be extensions on one account?