Notruf Emergency Call Support

Notruf is an single emergency line for German networks that uses geolocation to collect and store a caller's information. The information collected includes party location and call center location/numbers. The Notruf for the SBC Core use Ribbon SBC call processing to collect information from the caller. 

Within this context, the primary objectives of this feature is to insert calling party location information, and to provide a dialed emergency number translation (if needed) for emergency calls within German networks.

The SBC is deployed in the customer network as Centralized Policy Server (CPS). The ERE need to work in conjunction with NBS5200 to support the mandated German emergency call concept requirements as per design. The design works as follows:

• Location database for all subscriber numbers in the customer network.
• Association of the stored location information with an emergency call setup and generate the location information signaling parameter in the egress emergency call request. An ISUP UUI parameter encoded in accordance with ITU-T Recommendation Q.763/Q.931 and “TR Notruf” Technical Directive on Emergency Calls will be used to carry the location information to PSAP.
• Translation of dialed emergency number 110 or 112 to corresponding PSAP address.
• Route the call accordingly through the customer network.

The latest update to the specification "BNetzA Technical Guideline for emergency calls (TR Notruf) Version 2 May 2018" specifies the enhancements for SIP interface when the PSAPs are upgraded to SIP interconnect. This specification adds the requirement to pass the UUI information in the SIP "user-to-user" header and introduces additional location information in the form of GeoLocation headers (RFC 6442) and PIDF-LO XML data (RFC 5491).

The deployment models considered for the German market include both Access and Interconnect, and the German market requires support for both Notruf 1.0 and 2.0 specifications for emergency call handling in the Ribbon SBC.

• The Access deployments require the Ribbon SBC to support SIP calls from the UEs and add the configured location information and route the calls to respective PSAPs. 
• Interconnect deployments where the Ribbon SBC may not add the location information on its own, but will relay the information provided by the access nodes. It may be required to interwork the Notruf formats based on the protocol towards PSAP.