Network Reliability Steering Committee (NRSC) Overview and NRSC 9-1-1 CAMA Trunk Throughput Optimization Analysis

1. Network Reliability Steering Committee (NRSC) Overview and NRSC 9-1-1 CAMA Trunk Throughput Optimization Analysis Stacy Hartman – CenturyLink Robin Howard – Verizon NRSC Co-ChairsSeptember 23, 2011

2. ATIS and Standards Development • ATIS is the leading technical planning and standards development organization committed to the rapid development of global, market-driven standards for the Information Communication Technologies (ICT) industry. • More than 600 industry professionals from approximately 250 companies actively participate in ATIS’ Committees, Forums, Focus Groups and Incubators. • These groups are comprised of leading subject matter experts and develop global technical and operational standards for communications using a pragmatic, flexible and open approach. • The groups focus on issues such as Emergency Communications, IPTV, Cloud Services, M2M, mHealth, Next Generation Networks and Services, Interconnection, etc.

3. Network Reliability Steering Committee • Addresses network reliability improvement opportunities in an open environment and advises the communications industry through the development of standards, technical requirements, technical reports, bulletins and best practices. • Addresses critical trends in the reliability of our nation’s wireless and wireline communications networks by: • identifying potential network reliability issues through an opportunity evaluation process; • establishing subteams to work specific reliability issues; • providing industry feedback to the FCC on network reliability and the FCC’s Network Outage Reporting System (NORS) and Disaster Information Reporting System (DIRS); and • serving as an educational resource on network outage trends and the industry’s ongoing efforts to resolve network reliability concerns.

4. Network Reliability Steering Committee • The NRSC also initiates special studies related to critical infrastructure reliability. Over the past 24 months, these special studies have included: • Cyber Security Best Practice Review • NRSC Proposed and Modified Best Practices (submitted to CSRIC II) • Best Practices Tutorial • Normalization of Reliability Metrics for FCC-Reportable Outage Data • NRSC CAMA Trunk Throughput Optimization Analysis • The NRSC actively partners with other industry groups to share knowledge. Joint effortsincluded: • EastWest Institute Worldwide Cybersecurity Summit • Telecom Energy Alliance • North American Telecommunications Damage Prevention Council • Association for Information Communications Technology Professionals in Higher Education

5. Network Reliability Steering Committee • CSRIC II Participation • NRSC participation on WG2A – Cyber Security Best Practices, WG4A - Best Practices for Reliable 9-1-1 and E9-1-1, WG4C - Technical Options for E9-1-1 Location Accuracy, WG6 - Best Practice Implementation, WG7 - Pandemic Planning - Priority Service Requirements • Best Practice Subcommittee • Partnering with the FCC to review the modified and new Best Practices ratified by CSRIC to: • Identify duplication and/or overlap within the existing Network Reliability Interoperability Council (NRIC) Best Practices; • Ensure each Best Practice has a subject title and/or tagline’ • Identify applicable keywords; and • Evaluate the Best Practices for additional ways to group them and/or make them more user friendly. • ATIS NRSC Best Practice Website, put online with enhanced features: http://www.atis.org/bestpractices/Default.aspx.

6. Network Reliability Steering Committee • Member Companies: • Alcatel-Lucent • AT&T • CenturyLink • Cox Communications • MetroPCS • National Communications Systems (NCS) • Sprint • Telcordia • T-Mobile • Verizon

7. NRSC 9-1-1 CAMA TRUNK THROUGHPUT OPTIMIZATION ANALYSIS

8. Overview • The NRSC was asked by the FCC on May 4, 2011, to review a 9-1-1 service-affecting issue that may occur during a sustained Mass Calling Event to 9-1-1 that causes a Focused Overload of the 9-1-1 system. • A NRSC subteam was created with participants from AT&T, CenturyLink, Cox, Telcordia, T-Mobile and Verizon. • Numerous subject matter experts from these companies participated in semi-weekly calls. • As part of this review, incidents of high call volume and the current 9-1-1 architecture were reviewed, as were situations in which certain 9-1-1 Selective Router (SR) platforms could remove 9-1-1 PSAP trunks from service during periods of heavy emergency call volume.

9. Architecture • Wink Failures can occur during heavy call volume events to 9-1-1 PSAPs and result in a 9-1-1 SR removing PSAP trunks from service during call setup. • These Wink Failures occur when a SR presents a new call to the PSAP over an idle trunk and the SR does not receive a supervisory OFF-HOOK Wink to signify the Customer Premise Equipment’s (CPE’s) ability to receive the ANI digits using MF Signaling Tones.

10. Upon two successive No-Wink conditions, certain legacy 9-1-1 SRs will remove the trunk from service. This would result in fewer trunks remaining to receive and handle additional calls. There is a potential that all trunks can be taken out of service due to a No-Wink condition; in this case, all incoming 9-1-1 calls would be routed to treatment if the PSAP has not requested an overflow route to another PSAP, administrative line, or other location to receive the call. The root cause originates from a timing or synchronization offset between the SR and the 9-1-1 CPE that can occur during periods of high call volume in which abandoned calls allow new calls to be presented before the 9-1-1 CPE is ready to receive the call. All CPE types may be susceptible to this condition and this problem is likely shared by many 9-1-1 SR Service Providers. Data Analysis and Root Cause

11. NRSC Recommendations • ATIS published its NRSC 9-1-1 CAMA Trunk Throughput Optimization Analysis Standard (ATIS-0100034), which provides recommendations to mitigate the condition of the double wink failure and to maximize 9-1-1 call throughput to PSAPs during high call volume conditions. • Short Term Recommendations, such as: • Where available, 9-1-1 system providers should modify translations in their SRs to disallow the complete trunk group to be removed from service due to double wink failures. • 9-1-1 SR Service Providers should update procedures to be more proactive in response to periods of high call volume to 9-1-1. • Long Term Recommendations, such as: • Update the PSAP trunk standards documents that are silent on the inter-call timing so that the industry, SR vendors, and CPE vendors are clear on PSAP trunk inter-call behavior in the future. • As possible, migrate off of the legacy SR to PSAP signaling standard to alternative industry compliant standards (such as NG 9-1-1 networks).

12. Summary • It is impossible to accurately forecast periods of high call volume, prevent a period of high call volume from flooding a 9-1-1 system with more emergency traffic than they can handle, or install enough network capacity to be able to handle all emergency calls during such an event. • With changing call patterns and more calls shifting from wireline to wireless, this situation may occur more often. • The industry believes that if 9-1-1 SR Service Providers and Public Safety Agencies take the steps outlined in the ATIS Standard, the 9-1-1 network will continue to operate as designed, and not inadvertently (or excessively) remove PSAP trunks from service. • The ATIS Standard is available to industry at no cost from the ATIS Document Center at: http://www.atis.org/docstore/product.aspx?id=25661.

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