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New Member

nat and voice problems

we are a very small network here with only one real ip and 10 local inside ip's

and we are using pat to map the group of local inside ips to one global ip but there are lot of problems occuring will using voice applications such as net2phone or so ...

why exactly is the problem occuring and what can i do on my 1600 router to prevent this while maintain using only one real ip

i ll appreciate an in depth answer

  • Other Collaboration Voice and Video Subjects
New Member

Re: nat and voice problems


I think I have a solution but before I go ahead, I will appreciate if you will mentioned which IP phone devices you are using and what call signaling (H.323 or SIP)?



New Member

Re: nat and voice problems

Hi yaron

unforyunately i am not any phone devices and i dont know what are you talking about "H.323 or Sip " the router is configured with very simple configurations (basic configuration)

can you still help under this circumstances ???



New Member

Re: nat and voice problems

Can you send me a copy of your config or post it. If you are just trying to use net2phone. What errors are you having.

New Member

Re: nat and voice problems

I think the issue might have to do with the fact that VoIP applications use layers higher than layer 3 in the OSI model, hence simple PAT is not helping. I have heard of many issues involving NAT and VoIP and a rumor circulated that cisco introduced an newer IOS with some commands that will make the NAT function "VoIP-capable" as well. I glanced at this news in a news group a while ago, and i don't have the specifics. But thought i will give you a hint anyway.


New Member

Re: nat and voice problems

Dear Naguib,

You can try and download the latest software client from Iconnecthere web site which is

This client is using SIP base call signaling and solved the NAT issues which are comment with VoIP session.

Let me know if you need additional guide.

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