fail safe survivability options protect business connectivity over enterprise IP networks using advanced alternative network consisting of PSTN or ISDN circuits via modems to ensure signaling between the host site and remote site. Survivability is offered through the Comdasys Convergence and the built in HG3540 Gateway's ability to fall back to native SIP, when the comdasys enters survivability mode. Redundancy is achieved with a hot-standby call controller.
The optional local trunking at remote site serves as the voice connections to the host site trunking in case of a total enterprise IP network failure. There will be an automatic PSTN fallback when the IP network is congested. This means that, should the IP network fail, remote sites are fully survivable, supporting internal calls, external trunk calls via local trunks, trunk calls between the host site and the remote site and signaling from the remote node to the main node via modem.
During normal operation, all SIP-Q messages between the Lotus Sametime Unified Telephony and are passed through the Comdasys proxy transparently. The Comdasys proxy is the primary destination for the built in HG 3540. When the Comdasys enters survivability mode, incoming SIP-Q messages are rejected which triggers the HG3540 to fall back to native SIP and the Call goes through. Outbound calls also use native SIP.
In case of a WAN failure the following will occur:
Comdasys proxy will forward all branch external calls via the GW to the target destination.
The limited Comdasys and local phone feature set is available for all branch office users.
Enhanced Lotus Sametime Unified Telephony features (e.g. group features) are not available.
Calls from the branch office to the headquarter are routed via the PSTN.
Calls from the Headquarter to the branch office are rerouted via the PSTN.
System Specific Information
Phones are registered directly at the Comdasys proxy:
The proxy acts as redirect server and forwards signaling to the Lotus Sametime Unified. Voice
No dual registration support is needed in case of WAN failure.
This branch office configuration supports for up to 1,500 users per Branch office
Covergence 1600/ < 50 user
Covergence 2600/ < 150 user
Covergence 3600/ < 1500 user
Survivable Branch Office using Mediatrix with Comdasys