Incoming and outgoing branch-office calls are normally routed to the head office by the Lotus Sametime Unified Telephony SIP server. All stations in the branch office can access the same applications as stations in the head office. Lotus Sametime Unified Telephony is reached from the branch office over the Internet/WAN. The RG 2700 SIP proxy checks the connection to Lotus Sametime Unified Telephony for call signaling. In the case of calls to and from the ISDN network, RG 2700 operates as a voice gateway controlled by Lotus Sametime Unified Telephony.
In case of a WAN failure calls from PSTN to phones in the RG 2700 branch are directly signaled. Calls from Lotus Sametime head office to phones in the RG 2700 are only possible if failure precautions have been taken in the head office.
In normal case, if someone in the branch office (device 1) calls a station in the head office (device 2) or an external station (device 3), signaling is performed via the central Lotus Sametime Unified Telephony. The gateway used for calls to the public telephone network depends on the Lotus Sametime Unified Telephony configuration. Either the gateway in the head office can be used or RG 2700. The actual connections between device 1 and device 3 are routed via the RG 2700 gateway, whereas connections between device 1 and device 2 are routed via the Internet/WAN (without transiting a gateway). Calls from device 3 to device 1 are routed via the RG 2700 gateway to Lotus Sametime Unified Telephony and from there to the branch office. Calls from device 2 to device 1 are signaled in the branch office via Lotus Sametime Unified Telephony. In the event of a disturbance on the Internet/WAN connection, the Lotus Sametime Unified Telephony SIP server and associated applications are not available for the branch office. In this case (survivable mode), the RG 2700 SIP proxy automatically routes external calls (every call outside the local branch) over the PSTN network. The range of features available in this instance is reduced. The user will be informed about the survivable mode with a message in the phone display. If someone in the branch office (device 1) calls a station in the head office (device 2) or an external stations (device 3), the RG 2700 SIP proxy sets up a call over the PSTN via the ISDN network.
Parent topic: Survivability Overview
RG2700 Media Gateway Survivability