CME SIP Trunk and Nat

[iwearing]

Hi,

I have a CME and have a requirement to use a SIP Trunk provider for external calls.

The CME Router will sit behind an  adsl Router which wll nat from inside to inside.. Due to the issues with natting SIP is this a workable deployment?  Any comments would be appreciated.

thanks

Ian.        

[paolo bevilacqua]

You can try, but chances are that will have issue like one way audio,

For sure and quick results give CME a public IP address, and appropriate protective configuration.

[Ayodeji Okanlawon]

Your router handling NAT will need to support SIP inspection to properly rewrite the SIP Headers, otherwise the other side is not going to get the right address in the SIP SDP for where to send RTP to.  These are usually calles SIP Application-Level Gateways (ALGs). This can be a CUBE or ASA or any 3rd party gateway that supports SIP inspection and rewrite

As Paolo mentioned the easiest approach is to use a public IP on your CCME.

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[Michael Ricci]

I've NAT'ed on CUCM with a SIP trunk before.

On the ICT's though you have to use the Public IP address of the distant end, and for obvious reasons you must use static NAT as well.

[paolo bevilacqua]

Michael Ricci wrote:
I've NAT'ed on CUCM with a SIP trunk before. 
On the ICT's though you have to use the Public IP address of the distant end, and for obvious reasons you must use static NAT as well.

Note OP is asking about CME not CM.

There is no concept of ICT on CME.