[Freeswitch-users] detecting if user available before bridge

Hello, I need to find if a user is connected to FS currently. That is, not only registered (I found how to detect that<https://wiki.freeswitch.org/wiki/Function_sofia_contact>), but for example if I can communicate with it's soft-phone. I need to know if the soft-phone crashed for example, and if not, then not to send the bridge command at all, but actually been able to do something back in my application because of it. Is there a way to send for example an "option" header of some sort to a specific user prior to bridge command, and know it's result ? Thanks, Ido