PSTN and Data Communications

WaldoMcFroog | 14:30 Mon 07th Nov 2005 | Technology

3 Answers

I'm doing research into a paper on the issues of using a PSTN (Public Switched Telephone Network) for data communications. I have identified a number of areas where I believe that there are major issues. In no order, these are:

1) Communications issues maybe outside of the end user's control - it may be with the PSTN, not their network, in which case, it can be difficult to get issues prioritised and fixed.
2) Bandwidth changes throughout the day due to consumer demand.
3) The data is slower through the last section from exchange to end user, since this typically is an analogue system. This means that data travels at the rate of the lowest bandwidth in the system.
4) The analogue portion of the line is more susceptible to noise, meaning signal to noise may increase, resulting in lower bandwidth.
5) PSTN reserves a dedicated 64kb for voice channels, therefore restriciting available bandwidth for data coms. IP only requires 8kb, therefore IP more efficient.
6) The signal may need to be converted from analogue to digital at more than one point (i.e switches). At each change, it it is possible that noise may be introduced, thus attenuating the signal.

Can anyone suggest any other major areas I need to research?

Many thanks!

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OBonio

Security might be worth mentioning. Though I suppose that applies to voice aswell as data (ie, an engineer will have access to the data via a phone tap).

Copper. Quite a few phone lines are still copper I think, though mainly out in the sticks.

Technologies not offered by PSTN like Frame Relay.

Little article on Frame Relay here :

http://www.argreenhouse.com/papers/jlj/interop99.pdf

drinki

Hi,

Most of the issues you have highlighted apply to the domestic market. SME & Corporate users will have dedicated services, which will have different issues mainly to do with capacity & security. Dedicated bandwidth should not be an issue
GD