ATIS - 1000006
Signalling System No. 7 (SS7) – Emergency Telecommunications Service (ETS)
|Publication Date:||1 April 2005|
To ensure that a survivable and enduring National Security/Emergency Preparedness (NS/EP) telecommunications capability is available during emergencies, the U.S. government has endorsed the development and adoption of standards to support increased call completion capabilities for critical users. The Emergency Telecommunications Service (ETS) would be applied during the call setup by providing an identifier for those calls in the SS7 network protocol. This identifier would allow ETS calls to be recognized as they are routed across and between networks so that call completion improvement techniques could be applied by service providers to increase the probability of completion during periods of network congestion or damage.
ETS in its most generic sense provides for preferential telecommunications connectivity for any authorized user from any originating point in the public network. ETS can provide various multimedia features to the user. This standard is limited to the set of features, such as voice, that can be supported by ISUP and BICC.
This standard specifies ISUP and BICC call control protocol enhancements and procedures to support ETS. When such a call goes over a BICC network, the call and bearer are separated and different types of bearer technologies (e.g., ATM and IP) can be used for bearer connection setup. Therefore, a priority indicator is required in bearer networks to identify that a connection set up is associated with an ETS call and to cause priority allocation of bearer resources. As the connection set up progresses through the bearer networks, this identifier enables special routing and preferential treatment to ensure the higher probability of connection establishment. The preferential allocation of bearer resources is maintained for the duration of the call.
The techniques used by service providers to enhance call completions in the network might vary from the application of special network management controls, to the invocation of special routing or queuing mechanisms, to partitioning and prioritizing completion of ETS calls. This standard does not describe any of these special routing or handling procedures in detail, nor does it describe the specific manner in which the user originating the call would indicate to the network the need to have the call so marked. These may be the subject of future American National Standards or may be provided by nonstandardized procedures based on agreements among network providers, service providers, and users. This standard also includes descriptions of some allowed options for recognizing an originating call as an ETS call, but these options are not exhaustive, and this standard does not necessarily require support for all options at every originating switch.
The service described in this standard includes these essential portions:
♦ The capability at the originating switch to authenticate the calling party and therefore to authorize the call as an ETS call;
♦ A special indicator carried through the network with the call set-up signalling to identify the call as an ETS call; and
♦ Use of higher MTP message priority level value for SS7 messages to increase the probability of successful transfer in the case of congestion in the signalling network.
This service shall not be used except as authorized by the appropriate U.S. government agency. The authorization mechanism is beyond the scope of this standard other than the prohibition for unauthorized use.