I have several Snom VoIP phones in the office running off a virtual phone system in London somewhere.
I've written a small PHP app that lets me control the phone remotely - all it does in the background is cURL into my handset's web interface and control it that way.
However now I'd like my PHP app to know what other phones on the system are available/busy. I think the phone handsets do this by way of a SIP subscription with the virtual phone system, whereby my handset subscribes to feeds from all other handsets on the system and can then light/extinguish the busy lamp.
Am I going about this the right way? Is there any way I can have a PHP script subscribe to those notifications?
Many thanks in advance