VoIP Specific Networking Tips / Ideas

[pablob]

Hello,

I am thinking of buying the ATA from FPL, but I'm worried about the port forwarding. I am currently using other SIP providers in my home network (mostly from my N900, but also from SIP clients on computers), and I worry that if I forward the SIP ports to the ATA I will lose the use of SIP on the other clients.

I have had success on my SIP clients without any forwarding. Could that mean that my router (Airlink 101 AR-525W) does the NAT properly and it would work out of the box with the ATA?

Or it might be possible to change the ATA ports so I can forward a different set of ports to it (and leave the standard SIP ports unchanged).

I will appreciate any information, thanks a lot!

Pablo B.

[FONGO_kris]

You can of course change the ports your ATA uses to connect.

I will be so bold as to say it is almost mandatory to make each SIP device connect through different ports to avoid any conflicts.

[pablob]

You can of course change the ports your ATA uses to connect, but keep in mind forwarding ports does not dedicate them to a device but only keeps traffic to and from the device undisturbed.

Great! I will probably try to order my ATA soon...

I had the impression that port forwarding as done in the routers (where you specify the IP of a device) esentially rewrites and routes packets received for a given port to the specified internal IP. As a side effect, no other devices in the network can receive an unexpected packet in that port (thus no inbound calls for devices other than the one specified in the case of SIP).

Is my understanding wrong or are you referring to some other type of forwarding? (NAT in the router does the proper "dynamic forwarding", but there is a problem with inbound connections since the router has no way of knowing beforehand to which internal IP to forward it to).

I hope you don't mind turning this thread into a discussion of network techniques, feel free to move it to a more appropriate forum or just link to a good informative text.

Thanks for the quick reply!

Pablo B.

[zombie999]

Pablo,

You do NOT need to forward ANY ports to use FPL. I see that your other devices are working fine. If so FPL will work fine with no port forwarding.

People who need port forwarding have crappy routers that are not VOIP friendly.

And yes, you are right, if you forward a port for FPL, your other devices that use the same port will not get a call. Because all traffic to that port will go to your FPL device.

You can have multiply SIP ATAs all using the same port behind NAT. No port forwarding needed. I know I do. 4 ATA's, all use same ports, no problems.