My specific use case is an inbound Skype call using mod_skypopen to a SIP phone.

I would like the Skype call to keep ringing as a Skype call (not a PSTN call)
until the B-leg is answered.  The default behaviour is the Skype call is answered 
by freeswitch and ringback is played over the established Skype call.

Thanks in advance,

Jason