Replacing the PSTN with VoIP: Not If, But When

Implications of the PSTN Retirement, Part One

As thirty-year telecom veterans, we’ve seen our share of changes in the Public Switched Telephone Network (PSTN) that includes the replacement of electromechanical switches with digital switching, the introduction of Signaling System 7 (SS7) and ISDN, the Class 4 Central Office conversion to softswitches, and the introduction of hosted VoIP services for consumers and businesses.   

Almost from the first day about 14 years ago when we started this newsletter (now also a blog), we’ve said that the question of business VoIP adoption is not a case of if but when; we have long expected that business voice services will transition away from to the legacy PSTN  to VoIP. The same now clearly holds true for the PSTN.  Replacement of the PSTN with a global VoIP-only network delivering service provider wired voice and wireless voice is not a question of if, but when.  

The PSTN to VoIP transition was always on the map, but now we are beginning the routes to get there, and we may even have an “estimated time of arrival.”  AT&T, for example, has been clear that its goal is to replace its legacy PSTN network with a fully VoIP infrastructure by 2020.  The implications of such a replacement are bigger than any transition we’ve seen in over 30 years.  PSTN replacement means, for example, that phone companies will no longer rely on SS7. The black rotary, analog dial phones still used by some will go the way of operator-controller cord boards.   

Still, the good news is that a whole world of new features like high quality voice and presence management will become available to all public telephone network subscribers.  Even the wireless network users will benefit with integrated VoIP features courtesy of a VoLTE (Voice over LTE) evolution. 

Over the coming month, we’ll take a look at some of the implications of the PSTN replacement in detail, looking at the issues that must be resolved such as carrier-to-carrier routing, feature interoperability, and security.   

Meantime, we also note that copper wires and digital broadband will not go away any time soon.  If fact, these will be needed to deliver VoIP, video, and Internet connectivity to most homes office at increasingly higher speeds.  For some more on this angle, we recommend a tech note written recently by our long time colleague Bill Flanagan titled, “VoIP, The PSTN Killer, Won't Kill Local Loops.” In his analysis, Flanagan explains how DSL advances will provide more capacity for new uses by using vectoring and other noise control techniques.  The article, published at Webtorials, can be found here.

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