This is all I get in the logs for one of the extensions:
[2019-10-18 04:30:03] VERBOSE[5501] res_pjsip/pjsip_configuration.c: Endpoint 3210 is now Reachable
[2019-10-18 04:30:03] VERBOSE[5501] res_pjsip/pjsip_options.c: Contact 3210/sip:[email protected]:5060 is now Reachable. RTT: 32.447 msec
[2019-10-18 04:32:06] VERBOSE[13145] res_pjsip/pjsip_configuration.c: Endpoint 3210 is now Unreachable
[2019-10-18 04:32:06] VERBOSE[13145] res_pjsip/pjsip_options.c: Contact 3210/sip:[email protected]:5060 is now Unreachable. RTT: 0.000 msec