[Freeswitch-users] how get billserc in dialplan?

Hi how get billsec in dialplan. i am try a condition after sched_transfer_time. <condition field="${cond( ${answered_time} >= ${duration} ? YES : NO )}" expression="^YES$"> i need check two time in seconds, without hangup the call example <condition field="${cond( 60 >= 30 ? YES : NO )}" expression="^YES$"> Thank