A system (100) for providing virtual connections through an ATM interworking multiplexer (130, 140) on a call-by-call basis. A signaling processor (160) receives signaling for a call and selects the virtual connection for the call. The signaling processor (160) generates new signaling that identifies the selection and transfers the new signaling to the ATM interworking multiplexer (130, 140) that accepted the access connection for the call. The multiplexer (130, 140) converts user information from the access connection into ATM cells for transmission over the virtual connection in accord with the new signaling.