Hello Taru,
According to what i under-stand, in case of conditional call forwarding the initial RRBCSM will set T_BUSY ( as u said) and then CONNECT is requested to Calling party “B”, if “B” is busy, then ERBCSM will be sent from SSP to SCP. On receiving ERBCSM with T_Busy set, the SCP will send a fresh connect with “C”‘s number. and call gets forwarded.
But in case of un-conditional call forwarding there will be not wait for any triggers and SCP will send CONNECT (only one CONNECT) with “C”‘s (tobe forwarded) number.
You can communicate to me for any more discussion on harish_kulkarni@hotmail.com
-Thanks
Hari