Today I had a user on a call and experience a disconnect. After investigating further, the following errors in the asterisk log were found for that extension. username mismatch, have <1109>, digest has <> NOTICE  chan_sip.c: Registration from '' failed for '192.168.x.x' - Username/auth name mismatch basically, my phone lost authentication and could not re authenticate? I'm certain that my credentials are correct and this effected multiple phones. What could cause this and how do you recommend I go about correcting it?. Thanks!