For some reason when I restart Asterisk, or the server running asterisk the DPMA module does not load properly. To get the phones to reconnect I have to reload the module (its auto loaded on asterisk startup) and issue a DPMA reconfigure phones command. otherwise the phones get stuck asking for the DPMA proxy server.
No issues with other phones: Cisco & Polycom phones. I tried using a couple of Digium phones to make adding and reconfiguring phones easier with DPMA. using DPMA version 3.2.2