FAQ-An External Phone Fails to Register With the SIP Server After a NAT Server Is Configured on the Outbound Interfaces of the Device Functioning as a SIP Server

Publication Date:  2015-05-05 Views:  174 Downloads:  0
Issue Description
An External Phone Fails to Register With the SIP Server After a NAT Server Is Configured on the Outbound Interfaces of the Device Functioning as a SIP Server.
Solution
A SIP server is deployed on an internal network and a NAT server and MTU are configured on the outbound and inbound interfaces of a gateway router on this network. In this case, the router sends fragmented packets to the SIP server and the server returns ICMP Error packets. An external phone fails to register with the SIP server. Disable the MTU configuration on the inbound interface or run the ip soft-forward enhance enable command to enable the enhanced IP forwarding function on the router, so that the external phone can correctly register with the SIP server to implement NAT translation.

END