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Is IP-based telephony inferior to POTS?

Posted: 03 Jun 2015     Print Version  Bookmark and Share

Keywords:POTS  PSTN  VoIP  Voice over IP  Smart Transform 

There will always be resistance to any efforts by network providers to swap the plain old telephone service (POTS) with all-IP alternatives.

I see that another attempt is being made to drive a stake through the heart of the two-wire plain old telephone service (POTS), also known as the Public Switched Telephone Network (PSTN). This time it is by Alcatel-Lucent and its PSTN Smart Transform.

Alcatel-Lucent says its PSTN Smart Transform consulting and design services to current POTS providers who want to shift to all voice-over-IP network will reduce migration costs 30-50 per cent, reduce end-user outage time during migration of 20 seconds compared to an average of 20 minutes by competing services, and migrate 99 per cent of their end-users without experiencing issues.

If this plan makes it to my PTSN provider, I will probably be one of that 1 per cent who will have "issues," no matter who is doing the conversion because I have just shifted back to a standard two-wire POTS line from my local telephone company. After numerous tries with different companies, I gave up voice-over-IP (VoIP) because it was maddeningly unreliable. And I find nothing in the material on the Alcatel-Lucent website describing Smart Transform that makes me regret that decision. The web page presents a good case to telephone service providers, but there is little on what it means to end users.

Limits of IP-based telephony

Based on my experience with Voice over IP (VoIP) systems over the last several years, I don't have much confidence in the all-IP solution Alcatel-Lucent is proposing. Here's why:

When you place a "regular" phone call using the PSTN, you use what's called circuit-switched telephony. This system works by setting up a dedicated channel (or circuit) between two points for the duration of the call. These telephony systems are based on copper wires carrying analogue voice or digitised versions of it over dedicated circuits from the home to a local central office where it is further compressed and transmitted as a whole to the receiving location.

POTS Network

The dependable POTS network. (Source: www.mackinac.org)

VoIP, in contrast to PSTN, uses what is called packet-switched telephony. Using this system, the voice information travels to its destination in countless individual network packets across the Internet. This type of communication presents special TCP/IP challenges because the Internet wasn't designed for the kind of real-time and deterministic communication a phone call represents.


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