A system for inter-enterprise telephony communications includes a central brokerage device that can receive a packet encoding a dialed telephone identifier generated by a first telephony device located in the first enterprise network, where the dialed telephone identifier is associated with a second telephony device located in a second enterprise network. The central brokerage device can also identify a network address of the second enterprise network using connectivity information if the dialed telephone identifier matches resolution information. The system also includes the first enterprise network, which can establish an encrypted communication link with the second enterprise network through a packet-based network using the identified network address if the dialed telephone identifier matches the resolution information. The first enterprise network can also establish a second communication link between the first enterprise network and the second enterprise network through a circuit-switched network using the dialed telephone identifier if the dialed telephone identifier does not match the resolution information.