Once I was asked by a client to see why he could not get through to one of the numbers.
I opened the asterisk console:
I told the client to make a call to this number, after which a notification was displayed:
NOTICE[C-00000736]: chan_sip.c:25450 handle_request_invite: Call from ‘207’ (192.168.2.2:5060) to extension ‘06600000001’ rejected because extension not found in context ‘sip-dialout’.
I counted the number of digits in the number, I realized that one digit is superfluous, accordingly such a number does not exist and naturally I did not register such numbers in /etc/asterisk/extensions.conf.
Therefore, in order not to display this notification, you must dial the correct number, or if the number was dialed correctly, then it is not registered in /etc/asterisk/extensions.conf, then you need to register.