The Lotus Sametime Unified Telephony provides rerouting of SIP calls for unreachable gateways or subscribers in the case of WAN failure or after receipt of a SIP response code indicating an error condition such as a bandwidth restriction (e.g. 606). The SIP calls can be of type off-net (to the PSTN via a SIP gateway), on-net (to another SIP network, such as Telephony Control) or to a registered SIP subscriber. A rerouting timer provides rerouting in case no response is received from the SIP gateway, SIP server or SIP subscriber after an INVITE has been sent to them.
Rerouting for SIP subscribers can rely on particular conditions:
The called subscriber has to be registered from a survivable branch (e.g. served by Comdasys with associated SIP gateway).
The called subscriber has to reside in that survivable branch. This means that the called subscriber is registered with its provisioned 'Survivable' SIP Proxy endpoint.
The called subscriber has a 'Survivable' SIP Endpoint (SIP Gateway - no SIP Proxy) provisioned as associated Endpoint and it is registered directly with the Lotus Sametime Unified Telephony. (in this case the first two points are not necessary)
The called subscriber has to have a valid public E.164 number.
The calling subscriber must be calling from a different survivable branch or must be directly registered with the Lotus Sametime Unified Telephony.
For calls to the PSTN via SIP gateways or for calls to another SIP server, rerouting can also be done in case no definitive response code (1xx, 200, 3xx, 4xx, 5xx, 6xx) is received after the Lotus Sametime Unified Telephony sends the INVITE message to the SIP gateway or another SIP server. For calls to another SIP subscriber, rerouting of the call is done through the PSTN rerouting is also done in case no definitive response code (1xx, 200, 3xx, 4xx, 5xx, 6xx) is received after the Lotus Sametime Unified Telephony sends the INVITE message to the SIP subscriber.
Parent topic: Survivability Overview
Group of Gateways
Branch Office Gateways
Other SIP Server
Advanced Gateway SIP Rerouting
SIP Rerouting Feature Impacts