How many ATAs can I use behind just one public IP address?

[nathanlhc]

I purchased the SIP configuration file 5 years ago. I've been very very happy with FPL.

I have only one public IP address since I'm a home user. Can I add more ATAs behind my router? And how many?

i intend to install one or two ATAs from my tenants.

[jshoup]

That probably depends on the router, but most routers should be able to handle it. The ATA connects out to the SIP switch, and on its way requests a pseudo-random port be opened on the firewall/router. The firewall/router will keep track of which IP on the inside (ie which ATA) asked for what, so it should work fine. If you use something like the PAP2T that has 2 lines already, you could add this one more ATA to handle separate lines for two tenants - the ATA will know what it has asked for specifically for each line and won't duplicate that.

On the SIP page of the PAP2T is also a RTP Port Min and RTP Port Max that define the range this ATA will ask to have opened. Tweaking these for each ATA to not overlap may also work, though apparently they should be set to values given by FPL (mine appear to be a small range, likely the default for the PAP2T).

Hope this helps.

[bridonca]

When using more than one ATA or SIP, it is not wise to have the router to try figure it out. It is much better to manually assign separate ports for each ATA, and make sure the ports do not conflict with other devices.

With Fongo, it is pretty easy. Fongo does not need port 5060 as a SIP port, so you can assign other ports to it. that means one ATA device can use 5062, another 5064, etc. You can save port 5060 for another VOIP provider that is not as flexible.

You also need to make sure you have a separate, unique RTP port forwarded to each SIP device. You can use any available port for RTP, but I would use something above port 30000 because not much uses that range. Some ATA devices need more than 1 RTP port, so assign a range. Make sure each ATA device has different RTP ports assigned to it. So you might have to adjust the ATA accordingly, and change from the default RTP options.