SIP Trunk through Internet

[fafalekf]

Hi all,

We are trying to make a SIP trunk between a CCM 4.2(1) and an other IPBX (Astérisk) accross internet.
For this first test we have directly connected the CCM to the internet with a ADSL modem. The server has 2 NIC (one in the LAN with private address, the other connected to the modem with Public address). So actually no NAT !!!
We made a call from an Cisco IpPhone (3000@192.168.0.xxx), it goes to Asterisk and the Phone which is called is ringing. But when we answer to the call, a packet from the Phone is sent to astérisk, then to CCM. But the phone answer to the public @ of the CCM (3000@82.73.XXX.XXX).
When the packet is received by CCM, this one is not understand because 3000@82.73.XXX.XXX doesn't exist (it's in fact 3000@192.168.0.xxx ).
So I just want to know if someone met this problem (and solution !!!). We are trying without NAT and Firewall, but after this is working, we are going to add Firewall and NAT.
we just want to begin with the easiest way to finish with the Final way.

Thx for help

Fabian

 

[fafalekf]

Nobody ???

Thx

 

[Alien88]

You have confused me here. Start over. and explain your IP addressing.

Scott
CCVP

 

[fafalekf]

Ok,

Forget all you see before. The only thing I try to do, is to make a SIP TRUNK through internet.
publicIp1 is the public @ of my office
publicIp2 i the public @ of the remote Pabx
The ccm ip adress is :192.168.0.3
So all internal phone are registered to this Ip address.
I have created a trunk to the publicIp2.
When I made a call with the pattern of the Sip trunk, the remote phone is ringing (Nice), but on the internal Ip phone(2051) ==> No ringback adn then no RTP stream.
The problem (after debugging with ethereal) is that the Remote PabX (asterisk) reply to the CCM with a SIP packet which has in his HEADER (2051@publicIp1), and the ccm doesn't know this extension ==> It doesn't exist. The extension is known by the CCM as 2051@192.168.0.3...
So can I change the SIP header ? Or is there an other to make a call (for exemple 2051@DNSNAME, the remote pabx should be ok for responding on this DNSNAME)..
Thx

 

[Neily]

couldn't you use a router/modem and forward the external IP to the internal IP??

 

[Leachen]

Try out Ingate Siparator

http://www.ingate.com,

Security SIP Proxy enabling true and secure NAT/PAT. Mini SBC solving not only NAT/PAT and SIP trunks to various CPE TS´s, but also advanced SIP routing with possibility to register into various ITSP´s (Vonege etc). Solving Fare End Nat Traversals (Incl S-RTP and TLS) enabling true mobility, not only with STUN.

 

[fafalekf]

Ok Thanks, but the I resolved the pb...
The pb was that there was no Nat Into Sip header packet.
So it was a huge pb because ccm doesn't make automatically address translation...
But on Cisco Ios router, i found the right command
" ip nat service sip" ...

Thx

 

[Leachen]

The fundamental problem seems to be that your CCM are not aware of the NAT issue involved, it just sends our the traffic on your external interface probably because your IP routing rules tells it to do so.

If you use an Ingate SIParator you would only have one interface on the CCM and direct the trunking traffic through the Ingate box that would take care of the NAT rewriting. We have similar installations with CCM or Asterisk even though I haven’t seen the combination yet.

 

[fafalekf]

No the pb is not the ccm...
Because it just fwd packets to router.
router makes nat mais only on the tcp header but not into the sip header packets...
that's why u have to use normal nat and nat inside sip packets through the command ip nat service sip

Bye