Попытался сделать через callerid.
...
endpoint/callerid = IvanIvanov <1001>
...
endpoint/callerid = PetrPetrov <1002>
+ в extensions.conf
exten => _1XXX,1,Dial(PJSIP/${EXTEN},,t)и получаю в консоли:
Unable to create PJSIP channel - endpoint '1001' was not found