[reSIProcate] REFER without Expire

[Niraj Roy]

 Hi,
	I have a sip client uses resiprocate-0.9.0-5019.
	When REFER message is sent to my application without Expire header,
resiprocate stack sends 400 BAD request.
	While I am also getting onRefer Call back.
	As per the RFC 3515 Expires in the REFER message is an optional.
	
	Can anybody shade some light on it how can I come out of this and
have proper behavior?

Regards,
Niraj