this is discussed here as well:
i am using a mysql back end. I see some repetition here which is not needed as clid is already present to store caller ids. I can set the real src value from within the dialplan but given that i have a rather large dial plan with multiple possible entries, i might end up overwriting it. Also, currently using a mix of older and newer versions of asterisk, and for reporting consistency i would need to implement this change across the board. I was wondering if there was some way of forcing asterisk not to update it.