Overview

SIP Proxy provides an interface for SIP communication between SIP devices and SIP Server components. It handles register requests, load-balances SIP transactions, and provides an alternative HA model, which supports deploying primary/backup SIP Server instances within the same HA pair across different subnets and does not require a virtual IP address.

SIP Proxy conforms to RFC 3261 (Section 16) for a proxy.

Cluster environment

When operating in a SIP Cluster environment with one or more data centers, the set of SIP Proxy instances can be divided among the data centers. SIP Proxy obtains the lists of SIP Proxies and SIP Servers configured in the cluster from the Voice over IP Service DN that is configured in the Cluster Switch object. SIP Proxy uses the geo-location option to identify SIP Servers that belong to a particular data center. Those SIP Servers contain the geo-location option with the same value as in the SIP Proxy configuration.

All endpoints of a particular data center are managed only by local SIP Proxies. SIP Proxy forwards all SIP messages from the endpoints to local SIP Servers or Feature Server. SIP Proxy can also forward outgoing messages to other data centers. Replication of registration and call data is performed across all SIP Proxy instances in the cluster.

SIP Proxy uses the Active out-of-service detection oos-check method for updating a list of active SIP Servers in a cluster and for detecting the primary SIP Server in an HA pair. SIP Proxy forwards SIP messages only to the primary SIP Server of the HA pair.