MSRP B2BUA Support for NG911

The Oracle® Enterprise Session Border Controller (E-SBC) supports Message Session Relay Protocol (MSRP) and Back to Back User Agent (B2BUA) networking for Next Generation 911 (NG911). MSRP is used for messaging and file sharing in Session Initiation Protocol (SIP), which is widely used in NG911 markets that utilize MSRP with either an MSRP application server or in Peer-to-Peer (P2P) mode. Such support enables (E-SBC) customers to deploy the E-SBC as a Public Safety Answering Point (PSAP). The E-SBC supports this functionality only on Virtual Machines.

In P2P mode, the E-SBC uses MSRP, SIP, and the Session Delivery Protocol (SDP) offer-answer to establish a TCP or TLS media bearer plane between two MSRP endpoints. For MSRP B2BUA operation, the E-SBC terminates the bearer plane from one peer, and routes the message to the bearer of the other peer that is also anchored by the E-SBC.

For client-server MSRP, the E-SBC terminates the TCP or TLS bearer plane from the client and then connects it with a separate TCP or TLS bearer plane initiated by the E-SBC towards the server.

In addition to terminating and re-originating TCP or TLS for MSRP, the B2BUA modifies the To-Path and From-Path headers of the MSRP messages. The following example shows the modifications to the MSRP "To-Path" and "From-path" headers during traversal:

Figure 22-1 MSRP Flow with No Middlebox Present