How to determine traversal calls?

[hashimoto.kotaro]

Hi all,

As we can see at the site below,

"a SIP to SIP call when one of the participants is behind a NAT (unless both endpoints are using ICE for NAT traversal)"

is handled as  a traversal call by VCS.

http://www.cisco.com/en/US/docs/telepresence/infrastructure/articles/vcs_traversal_call_license_usage_kb_168.shtml

But how does the VCS know that one of the participants is behind a NAT?

Does VCS check if there is a difference between a value of "Via" header in SIP header and "C" type in SIP body?

Best Regards,

Kotaro Hashimoto

[Tomonori Taniguchi · Accepted solution]

If SIP UA’s sip contact address differs from source IP address, then VCS will determine this SIP UA is behind a NAT and treat as firewall traversal client/call.

[Tomonori Taniguchi]

This is a reason call will treat as non-traversal call on some of Jabber Video (Movi) public deployment with mobile connection (i.e. 3G mobile card) where IPS assign public IP address on client PC directly.