PSTN Transition Study


The yearlong debate and discussion over the PSTN Transition has finally met a milestone with the release by the FCC of a Report and Order, Further Notice of Proposed Rule Making and other initiatives involving Numbering Data administration.

These are all useful things. However, the public policy debate is far from over. There is substantial opposition to various aspects of the Transition. News reports about the Transition have often been unclear and there are inaccuracies on the rationale and scope of why this has been taking place.

There is a latent public perception that the phone companies want to turn off Grandma’s land phone without considering the real features and benefits of the transition, not just for consumers, but for enterprises as well. For example, caller-ID spoofing is a real and high-priority problem today. There are numerous approaches being developed for the all-IP network today. Conversely, there is no solution in sight for the PSTN, and even if there was, it would require massive capital investment in SS7 infrastructure – infrastructure that is slated for decommission. Likewise, all-IP networking equipment is plentiful and often benefits from enterprise IT economies of scale. PSTN networking equipment is at the other end of the spectrum: equipment manufacturers have declared the end-of-life for much of the PSTN infrastructure; there is little investment in new technology; and as a result it is almost impossible to find spares for many deployed systems.

Likewise, many people are missing the capabilities, besides fixing the caller-ID spoofing problem, the all-IP network will bring. Things such as individuals being able to text an emergency call, the ubiquitous availability of communications for the hearing, speech, and visually impaired, and facile integration of enterprise applications with the communications infrastructure to bring new and useful applications to consumers as well as enhancing business operations are all made available through the all-IP network. In short, the all-IP network brings far more than just changing TDM transport for IP transport. Yes, a “plain old telephone call” will still be a simple, end-to-end telephone call. People with black phones will still be able to call other people with black phones. However, so much more will be available for many more people.


It is clear that there are several issues that the public at large and the DC public policy community are not aware of. The Recent Report & Order highlights some key concerns that need further investigation and outreach.

Public Safety It has not been made clear the Transition is actually an enhancement to public safety. The underlying technologies of the Transition and NENAi3 are essentially the same. This will enable ubiquitous real-time voice, video, text and data to first responders thought the system. As well, support for law enforcement agencies could be enhanced, not diminished, by the transition. However, there are open concerns, like upgrading of existing equipment in light of diminishing budgets, the less than stellar experiences with attempts to have single device / multiple waveform radios, and the extremely long time it takes from concept to legislation to funding to procurement.

Reliability TDM networks historically advertised 5x9’s reliability. However, they never actually delivered that reliability in practice. The very nature of IP networks, with their enhanced resiliency permit the rerouting of emergency calls and other communications from one physical location or another nearly instantly.

Universal Access The continued existence of parallel networks, TDM/SS7 and IP, create disincentives for broadband deployment as maintenance costs on the TDM side eat into both CAPEX and OPEX budgets. This reduces the funds available for broadband build-out. On the other hand, we have regulations in place that ensure that every citizen has access to communications. Will the transition to an all-IP network eliminate the "social contract" to connect everyone?

Consumer Protection There is a perception the Transition might erode basic protections and the social contract inherent in the PSTN. Today there has been ample deregulation at both the state and Federal level. Yet there is no evidence consumer protections are going to be removed. Every telco service provider has emphasized that point. In fact, the recent efforts to develop methods to block Caller ID spoofing indicate the engineering community is well aware of the current level of risks from the Transition.

Competition The transition could enhance competition by permitting innovative service providers the opportunity to deliver competitive services over any IP network with significant enhancements such as HD Voice. Or, it could stiffle competition by concentrating access networks in a small handful of national providers.


This project consists of three deliverables. The first is a green paper to outline a course of dialog and highlight issues and facts to help guide a discussion. The second is a workshop to collect stakeholder input and to set the stage for discussion on the Transition to the nation and each stakeholder group. The third is a white paper with the consolidated results of the research and workshop.