Does Minisip support PRECONDITION ?

[daniele-_-_ at libero.it]

HEllo again,
I'm sorry but I'm driving crazy to solve this problem, I hope you can help me.
I'm building a Test bed to Interworking between Sip Network and IMS networking. I have read that if a Minisip (that work on Sip network) receive an Invite with "Require :precondition" from a Ims Ua, Minisip answer with a 420 Bad Extension (Unsupported :precondition) , since Minisip doesn't support precondition.

The problem is that in my laboratory, Minisip answer with a 180 (ringing),it means that Minisip accept the calling from a Ims UA.

I need the 420 message because it active a server in my laboratory.

I hope someone can help me.

Regards