Hi Jagan,
There is no option to introduce ringback on CUCM as CTI RP or CTI port would just be doing a CFA to CUC. A possible workaround would be to introduce another call handler which would basically answer the call and play ringback and then set the after greeting action to transfer to call handler 2 which would play the auto attendant.
Call Flow would become:
GW >>> SIP >>> CUCM >>> CTI RP >>> CFA >>>> CUC (Call Handler 1)>>>> Plays Ringback greeting >>>> After Greeting Action >>>> Call Handler 2 >>>> Play the auto attendant
Regards,
Aseem Anand
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