So, it turns out this wasn't an issue with the MX, but rather an error in each extension within Free PBX:   it seems that for the non-working extensions the “dial” is only the digit 1 instead of the full extension, committing the second and third integer…ext 103 and 112 work and are proper.   In correcting this, all is well   [root@freepbx ~]# asterisk -rx ‘database show DEVICE/100’ /DEVICE/100/default_user : 100 /DEVICE/100/dial : PJSIP/1 /DEVICE/100/tech : pjsip /DEVICE/100/type : fixed /DEVICE/100/user : 100 5 results found. [root@freepbx ~]# asterisk -rx ‘database show DEVICE/103’ /DEVICE/103/default_user : 103 /DEVICE/103/dial : PJSIP/103 /DEVICE/103/tech : pjsip /DEVICE/103/type : fixed /DEVICE/103/user : 103 5 results found. [root@freepbx ~]# asterisk -rx ‘database show DEVICE/102’ /DEVICE/102/default_user : 102 /DEVICE/102/dial : PJSIP/1 /DEVICE/102/tech : pjsip /DEVICE/102/type : fixed /DEVICE/102/user : 102 5 results found. [root@freepbx ~]# asterisk -rx ‘database show DEVICE/112’ /DEVICE/112/default_user : 112 /DEVICE/112/dial : PJSIP/112 /DEVICE/112/tech : pjsip /DEVICE/112/type : fixed /DEVICE/112/user : 112 Thanks again for all of your help! ... View more