Patent ID: 9049051
Filing Date: 2015-06-02
Classification: H04L,H04M

Abstract:
1. A method, comprising: providing a communication system to receive a call request at a branch office, the communication system including a gateway, a first network interface to a placket-switched network, and a second interface to a circuit-switched network; receiving at a call router in the gateway, a call request for an internal call terminal of the branch office; determining at the gateway that the call terminal is unavailable to complete the call request; determining at the gateway that a packet-switched network is unavailable to complete a packet-switched call connection to a data center having a messaging server, the data center being geographically remote from the branch office and operative to provide a unified messaging service for all internal call terminals serviced by the branch office and communicates with the branch office via the packet-switched network and the circuit-switched network; establishing a circuit-switched call connection with the data center from the call router via a circuit-switched private branch exchange (PBX) in the branch office to route the call request to the data center over the circuit-switched network when the packet-switched network is unavailable; and sending dual-tone multi-frequency signals representing call terminal identification information uniquely identifying a mail box for the call terminal from the gateway to the data center over the circuit-switched call connection to allow the messaging server to record a message for the call terminal.