- A TechNote on Infrastructure and Performance & Unified Communications
- Larry Hettick, Editorial Director & Senior Research Fellow, Webtorials
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 implications of such a replacement are bigger than any transition we've seen in over 30 years--including the PSTN's move from analog to digital and the introduction of SS7 back in the early 1980s. PSTN replacement means that phone companies will no longer rely on SS7 and that the remaining legacy TDM switches will become boat anchors. The black rotary, analog dial phones still used by some will go the way of operator-controller cord boards.
Phone companies have many reasons to retire the traditional PSTN. For starters, in the past decade traditional carriers like AT&T, CenturyLink, and Verizon have lost over half of their switched access lines to mobile substitution -- and to competition from next-generation providers like the cable companies who use VoIP in lieu of TDM. Cord-cutters prefer the convenience of mobile devices compared to a wired phone. Those who opt for VoIP services prefer the features already included with standard VoIP. As the customer base for PSTN services continues to decline, the costs of running a TDM and SS7 network supporting the PSTN are a catalyst for its retirement.
Operators such as AT&T and Verizon who also run a wireless network have another reason to move to VoIP: they also plan to transition their 3G voice network to Voice over LTE (VoLTE.) As VoLTE ultimately replaces the legacy mobile voice infrastructure, the mobile spectrum needed to support 3G can be diverted to 4G LTE networks which are much more efficient for supporting mobile voice and mobile data. Running a common core, voice-over-data network that uses IP session control multiplies the efficiency for both wired and wireless voice network operations.
Carriers aren't the only ones who will benefit from a transition from the legacy phone network to VoIP. Users have access to a broader range of features with VoIP, frequently for little or no charge. For example, traditional wireline phone services typically charge customers extra for long distance or value added services such as caller ID, integrated directories, and voice mail; however, most VoIP services come bundled with these features for no extra charge. VoIP technology also enables other features not available from the PSTN such as high definition (or wideband) voice, presence, click-to-call, and softphone options.
VoIP also establishes a platform for further integration of future services. Many enterprise users who use a premise-based unified communications (UC) platform today can shift between audio and video calls, and many cloud-based UC platforms are also starting to enable this feature--a feature made easier by replacing the PSTN with an all VoIP network. As other IP-based platforms and applications such as WebRTC are enabled, a cloud-based core VoIP network will also be ready-made to integrate these future features.
Finally, there are also environmental reasons to replace the PSTN with VoIP because a VoIP infrastructure is much more energy efficient that legacy TDM switches. By using less energy, VoIP platforms also reduce the global carbon footprint when compared to the TDM infrastructure.
To summarize, carriers and users alike have many good reasons for replacing the PSTN with a VoIP-based cloud infrastructure. However, the transition from PSTN to VoIP won't be without its problems. I'll cover the potential pitfalls and how to solve some of them in my next tech note.
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AT&T is at the forefront among tier one carriers for making a rapid conversion to VoIP, with plans to retire their PSTN and SS7 network by 2020. As born out by their recent notice about service terminations discussed recently here at Webtorials (see AT&T Issues Withdrawal of Service Matrix and AT&T Expands Withdrawal of Service Matrix), this is a major cause for concern for the enterprise.
Also. AT&T plans to have 70% of the network managed as a SDN by 2020, so the next five years are sure to be exciting, both for the telcos and for their customers.