CONTACT or VIA TCP port in noNAT environment

Hi everybody,

I'm working around a strange problem on an old 4250 6.2

 

In a Realm (connected to Internet, public IP) with SIP-NAT activated,

when endpoint connects TCP with L3, VIA and CONTACT with same IP address (noNAT environment),

SBC seems to use CONTACT TCP port instead of VIA one.

 

If endpoint connects TCP in the same REALM arriving from a NAT ROUTER, everything is OK.

 

It seems SBC apparently make a mistake using CONTACT TCP port (usually endpoint puts 5060-5069 random),

intead of using L4/VIA TCP port (usually > 32000).

 

Anybody can clear me this environment?

 

Regards,

Francesco.

 

P.S. Endpoint is BroadTouch UC-1 and soswitch is a Broadsoft AS.