Can SIP Client works with NAT CUCM?

[hiepnguyenho]

Dear all,

My company has a CUCM 7.0. I have implemented some Nokia E series phone with SIP connection to CUCM and they works fine. I have one question to ask:

If I NAT my CUCM to a public IP address on internet, can I connect my Nokia phone to CUCM by public IP? My goal is helping users connect to their phone number everywhere from their Nokia phone by Internet.

Thank you very much.

[paolo bevilacqua]

You must use VPN to connect phones on the Internet.

Nothing else is guaranteed to work, beside is not secure.

[hiepnguyenho]

Thanks for your answer. I think about this solution because I know there are some public SIP servers so we can directly connect to this server by nokia phone. Asterik can also work by NAT. But that is so sad if CUCM can not

[paolo bevilacqua]

The point is not that CUCM works or doesn't work with NAT.

The point is that is a bad practice to connect phones on the internet directly to it.

[hiepnguyenho]

Yes.. You're right. But my customer really want to use IP Phone this way, so I have to try to find out how it's work.