The SBC supports SIP for Business (SIP-B) protocol which outlines advanced SIP features for business telephony networks. Example SIP-B features are shown below.
With N-way calling, multiple contacts are associated with the same Address of Record (AoR). A conference server returns back its identity in the user part of the Contact header in the 200 response for an INVITE request. It also includes focus parameter in the Contact header to indicate that it is a conference focus. When transparency is enabled for contact header then ‘infocus’ is passed transparently to the other side.
Example CLI command to enable N-way calling:
SIP-B uses Instance-id to identify a particular registering device. A "sip.instance" feature tag is used in the Contact header of SIP requests and responses. Each device is expected to provide a globally unique instance-id. The SBC does not need to rely on this value for its own processing. When transparency is enabled for contact header then instance id is passed transparently to other side.
SIP-B uses P-Asserted-Identity to send called party identity. P-Asserted-Identity is allowed for certain request types. The SBC supports transparently passing this parameter.
If “relayNonInviteRequest” flag is enabled, Out-of-Dialog requests like REFER and SUBSCRIBE/NOTIFY are relayed using a route look-up to the ERE based on the request URI.
Example CLI command to enable relayNonInviteRequest flag: