SIP Proxy Server with NAT IP Phone

[riteshjalan]

Hi All,

We are facing problem in registering the IP phones and Cisco ATA who are behind symetric NAT.

What is the solution for this? How can a device behind symetric NAT can work/communicate with a Cisco SIP Proxy Server which is on a public IP address.

[lisa.hall]

The NAT Support for SIP feature allows SIP embedded messages passing through a router configured with Network Address Translation (NAT) to be translated and encoded back to the packet. An application layer gateway (ALG) is used with NAT to translate the SIP or SDP messages.

http://www.cisco.com/en/US/products/sw/iosswrel/ps1839/products_feature_guide09186a0080087d43.html

http://www.cisco.com/en/US/products/hw/phones/ps379/products_administration_guide_chapter09186a00801b1b06.html