[subhro]

Freeswitch is more complicated and has a steeper learning curve, but you can pair it with FusionPBX and it will make things a lot more palatable. Asterix is the grand daddy of this stuff. The community is stronger for Asterix. Freeswitch is pretty much infinitely customizable.

SignalWire is the primary sponsor of Freeswitch but is mainly geared towards HUGE installations. BulkVS is cheaper and better in my opinion. You can also look at AnveoDirect, which is more raw than BulkVS, but you can become really really fancy with it. Like, call center fancy.