double nat

[andymars]

there's alot of information on the internet saying that VoIP when used with double-nat is a bad idea... i'm unfortunately in this position and wondered what anyone else had done, if anything, to solve using voip phones behind double nat?

we're using an office network that I have no control over (except for the router in our own office) and so my chances of not having a double NAT setup are slim. does anyone have any thoughts/suggestions?

 

[andymars]

as i said, if i dont have control over the connection, what option do i have?

 

[leejor]

VPN?

 

[andymars]

VPN through double NAT? suppose that would have to be PPTP and not IPSec, certainly worth a go

 

[SY]

tunnel proxy?

 

[andymars]

the softphones do work using the 3cx tunnel (behind NAT and double-NAT), so there's no reason why it shouldn't work with the phones, but i'm using the Grandstream GXP2000 so how would I configure a tunnel from the phone itself? I'm not sure it's possible...

 

[SY]

the softphones do work using the 3cx tunnel (behind NAT and double-NAT), so there's no reason why it shouldn't work with the phones, but i'm using the Grandstream GXP2000 so how would I configure a tunnel from the phone itself? I'm not sure it's possible...

You can use stanalone tunnel proxy in the network which is behind "double nat" (it requires additional PC). Grandstream GXP2000 should work fine through the tunnel.
Why it is not acceptable solution for you?

 

[andymars]

i'll give the tunnel proxy a go, i read http://wiki.3cx.com/documentation/networking/sip-proxy-manager - which is probably the tunnel proxy you are referring to. i didn't realise that the 'tunnel proxy' was a seperate piece of software, should this work behind double nat?

 

[SY]

i'll give the tunnel proxy a go, i read http://wiki.3cx.com/documentation/networking/sip-proxy-manager - which is probably the tunnel proxy you are referring to. i didn't realise that the 'tunnel proxy' was a seperate piece of software, should this work behind double nat?

Yes, I'm referring to this software. If TCP connection with PBX host can be established from the network then it should work.
In any case, you need to verify acceptability of this solution on your environment.

 

[andymars]

it works well, thanks