http://wiki.freeswitch.org/wiki/Misc._Dialplan_Tools_valet_park

Like the wiki says, valet_park puts calls into numbered parking stalls. A call that is parked in a numbered stall is retrieved by calling (or transferring) a second call into that numbered stall. That makes it easy to pass calls around. The regular park app puts calls in a special park state that is like being on hold, but the only way to get them out of park is to uuid_bridge a second leg to the uuid of the parked call leg.

Read the wiki entry on valet_park and then read the one on park and you'll see that they are similar apps but the valet_park app is a bit easier for phone users to use for moving calls in and out of the park state.

-MC