could we test SIP over NAT device using the VIAVI Testcenter ALP?
Knowledge Base - FAQ
could we test SIP over NAT device using the VIAVI Testcenter ALP?
No:
This is an industry wide problem. Not an STC issue. When SIP client sits behind a NAT, it is un-aware of the public IP address. The SIP client is only aware of its local IP address (ie. 192.168.0.100). For NAT traversal to work properly, there needs to be either STUN or ICE support. The network must have STUN or ICE server. Alternatively, a SBC can also be used. SBC can inspect SIP packets and detect from the SDP, that SIP endpoint is behind the NAT and will remap the local IP to public IP. These are just a few options. Please refer to article below;
http://www.ag-projects.com/publications-corporate-176/151-best-practices-for-sip-nat-traversal
Unfortunately, you can’t just test SIP behind a NAT and pray that it works. There are various applications and network elements that make this work behind the background.