Toll Free Call Transfers

Does anyone know of any company covering the US & Canadian markets that offers an inexpensive service that would allow me to use my toll free number with extension numbers so that when a particular extension number is entered, the call is “handed off” to another toll free number (with another carrier) associated with the extension number entered, with, more importantly, billing on the first toll free number ceasing after the “hand off”.

I’m looking for a different way to offer a shared-use vanity number service from the ones currently offered that route to toll numbers and involve alot of separate billing on the initial toll free number called.