I have been created a softphone that create udp packet of registration sip and then encrypt udp packet and sent to Asterisk PBX. Because of the udp packet is encrypted, the asterisk could not handle it. i need when th packet is arrive in asterisk, in first decrypt it and then handle it. I use sip protocol. where could i add my code in asterisk source code? Is it true to add my code in chan_sip.c ?