I'm looking for a way to unpark a call remotely.

I have this scenario that involves Kamailio as registrar and proxy, and I'm sending calls to FS whenever an user is busy and can't pick up a call. This call is parked by FS.

When Kamailio detects the user in question got available, I want to unpark the previous call and connect it to the original destination.

Any ideas on how to do this in a clean way? 

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