Reject incomming call gsm module sim808

Hello good day to you!
i have an arduino uno hooked to gsm sim808 sim808 evb-v3.2 module, all command are exucuted from serial monitor, everything is ok AT command recive OK,
when i call the module it show ring with +CLIP: "Phone number",129,"",0,"Name",0
i want to reject the call just after i recive it
if i tape ATH or AT+CHUP it take 20 second to reject the call, the command return is OK

Any one have solution to quick responce rejecting call after sending ATH command or AT+CHUP

my goal is to make call with numbers to the module, after that the module reject that call and call back the recived number quickly.

thank you and have nice day.