ACD Ring Problem

[sameh]

hi all

I have oxo system with ACD (5 agent) only

i put all agent in same group

when external caller called with the call center (agent group)

the agent set sequence ringing until call response

but if the external caller closed the call after call are response the agent set remain ringing sequence

please some one tell me how i can cut call when caller closed his call

thank & beast regard