The third party devices (legacy paging devices) are registered in CUCM. While using JTAPI to request all the address in this provide's domain, the third party devices are not visible. Did Cisco JTAPI can see these third party devices as end-point address?
Cisco JTAPI returns only the addresses of the Cisco Terminals (phones) in getAddresses() API. Only the addresses configured in the users control list are returned. Third party devices are not CTI controllable/supported.
We figure out how to directly talk to the third party devices to identify status. It's limited information, but good enough.