There could be such a system but I'm guessing here as I am writing some M2M (see google) and each line/GSM/system would run about 200+ and then you would have to get someone to code it up and do the electrical work to switch your headset.
I'm thinking the first system should run about 100K.
I want to connect multiple mobiles USB modems with multiple Provider GSM CDMA with different no. and sim to my PC and want to dial calls through head phone through a dialer software from PC.
But i want that the dialer should be clever to dial the specific number from the respected Service provider (as mentioned in the software policy or filter)it should route redirect the outgoing calls to the respected GSM CDMA Mobile phone modem without knowledge of the Operator and can redirect the calls working as local Intercom, PBX, Predicative dialer or a smart phone dialer