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The transition away from legacy analog 9-1-1 networks to a nationwide IP-based next-generation 9-1-1 (NextGen 9-1-1) architecture is underway. This is a monumental transformation for public safety, exceeding the work of a decade ago to incorporate wireless Phase 1 and Phase 2 functionality. The implementation of next-generation capabilities will redefine the ways in which public safety answering points can communicate and interoperate with each other and it will revolutionize the types of services they can offer to the public. With this new IP-based connectivity, PSAPs can support more next-generation functionality and this presents significant opportunity for wireless carriers as well. When emergency services switch over to NextGen 9-1-1 and the underlying emergency services IP network (ESInets), it represents a new era in which wireless carriers can reinvent how their customers reach 9-1-1. This redefinition of capabilities is most pronounced for those carriers who have adopted voice-over-LTE. VoLTE, like NextGen9-1-1, is about using IP networks to move beyond the legacy telephony networks and protocols, the same sort that have defined 9-1-1 connectivity for nearly 40 years. Together, NextGen 9-1-1 and VoLTE will provide for more efficient and cost-effective network connectivity and advance the cause of continuously improving emergency services for subscribers.
Out with the old
Traditionally, wireless calls traversed a circuit-switched network from send to end. When wireless data was introduced, an entirely separate packet-switched, IP-based network carried that information. For years, voice and data were separate entities.
Today, with the enhancements of IP network speeds and reliability, voice has transitioned to data, and circuit-switched networks are falling by the wayside to make room for voice-over-IP networks. While these advancements introduced improvements to the quality of communications, they created challenges for wireless carriers who still require a means for connecting their customer’s 9-1-1 calls to analog circuit-switched PSAPs. Thus, protocol conversion and media gateways were introduced to bridge and transcode 9-1-1 calls from IP networks to legacy circuit switched networks to meet the FCC mandate for wireless E9-1-1 calls. While these network add-ons make it possible for carriers to deliver wireless calls to legacy PSAPs, they introduce inefficiencies to the network call flow, and carriers still need to maintain separate data and voice networks. Naturally, there will be a significant time period for this SS7 to IP transition. Wireless and public safety networks must work with each other to ensure blended technology environments do not harm reliable 9-1-1 services.
While the 6,000-plus PSAPs in North America are considering the scale and scope of change which NextGen 9-1-1 entails for their systems and governance, there is a similar large scale technology change at work in the wireless industry. The implementation of VoLTE in the cellular industry is the first large scale network disruption after two decades of optimizing the bearer paths for voice over circuit-switched SS7 networks. VoLTE requires wireless carriers to revise their past work and now focus on optimizing the data paths with quality of service markings applied to multiple IP bearer channels that carry IP voice, IP location, IP messaging, IP presence, etc. It is a large amount of work, but the benefits are significant enough to justify the effort.
VoLTE leverages the pure data network of LTE much like NextGen 9-1-1 leverages the pure data network of an ESInet. Interconnection options should benefit from common, more configurable IP protocols in order to sustain high quality and reliable request for assistance that are originated from the VoLTE network provider. VoLTE will have lower transport costs and greater performance management options while supporting the best practices learned over decades of legacy network 9-1-1 operations. In essence, the implementation of VoLTE allows carriers to surpass customer expectations for emergency calls thanks to the transfer of voice as an optimized application over a prioritized IP data network. While carriers will still need legacy gateways to connect to traditional PSAPs, the reality is that PSAPs from coast to coast will eventually transition to an IP-enabled next-generation entity. In fact, more and more PSAPs are starting that transition every day. One can expect then that carriers and PSAPs will each move toward next-generation IP capabilities at their own pace and given the fact that VoLTE is an IP solution, its proficiencies compliment the effort necessary to integrate wireless based voice services to IP-enabled PSAPs.
Improved location information
For PSAPs, location information is a core element for dispatching help to the scene of an emergency, yet obtaining that information has been problematic for wireless calls. Traditional PSAPs were built to receive calls from wireline telephones with a fixed location. The evolution of mobile phones with dynamic location and no fixed service address required the introduction of additional network elements to derive the location of the caller. Every network element created an additional opportunity for errors and failure. With the introduction of VoLTE, all of the 9-1-1 location and switching elements will be replaced with IP-based standardized protocols and network elements. LTE networks also use a new location determination protocol that is supported in two ways. The first is commonly associated with a control-plane design and the second is viewed as a user plane-based solution.
The control plane solution allows a carrier to provide a reliable and secure location for the communication link, an especially critical aspect for determining a 9-1-1 caller’s location. Once obtained, the location information is inserted in an IP-based communication session and forwarded to further elements in the core network that translate the data into the format required by an ESInet or a PSAP – be it IP-enabled or legacy. Retaining the IP nature of the location determination is a priority for any ESInet or PSAP and makes VoLTE a solid 2G/3G replacement strategy for any carrier facing the ever-growing number of NextGen 9-1-1 deployments.
Looking forward
There is one thing that is certain in the world of communications: change is happening all around us. For public safety, legacy equipment becomes more outdated and more difficult to maintain everyday. To combat this reality, the move to a nationwide all-IP network has begun and will certainly not slow down. For carriers, the evolution of VoIP capabilities optimized for LTE provides an opportunity to simplify networks and eliminate outdated technologies while introducing a new level of resiliency and reliability.
The future of VoLTE and NG9-1-1 working together to provide advanced emergency services to customers and citizens is the best end result realized from this period of large scale transition from circuit switched to IP networks.
