Software Musings

Telephony

Posted on: 07/05/2007

I’ve worked in telecommunications for a long, long time. It must be getting on for 30 years. I started with basic analogue telephony and have watched transmission move first to plesiochronous at a giddy rate of 2 Mb/s and then to synchronous transmission. I have seen what was transmitted move from analogue voice to various forms of “high-speed” data: Frame Relay, ATM and now IP. I have seen signalling move from being in-band to being out-of-band and now back to being in-band.

Why this reminiscence? Last December my wife and I, through no fault of our own, became grandparents. Our daughter, son-in-law and grandson (of whom there are now 99 pictures on the family photo’ site) live in England, some 5362 km away. So we installed Skype and managed to look at the grandchild (whom I have never seen in the flesh but, from his photographs he seems to resemble Sid James of Carry On fame) using the Skype voice and video service.

Now the video is pretty poor and not only out of sync with the speech but actually trailing it. Watching a cricket match one is used to seeing things before hearing them but hearing them before seeing them is a new phenomenon. But at least there is a video stream, something not offered by our landline carrier.

To assist my mother-in-law, to whom computers are strange and alien, we took out a Skype-in number in Cardiff (Wales), where she lives. So she can now call us for the cost of a local call. This is a service that few landline carriers offer.

Our long-distance calling charges halved in the months following the introduction of Skype but the landline PSTN continued to offer two advantages: sitting by the computer wasn’t mandatory (including running upstairs to the computer when a call came in) and it could make emergency calls (999 or 911 as they say over here). One of those advantages has just gone away. I bought my wife a Netgear SPH200D cordless telephone for her birthday and it arrived this evening. The basestation plugs into the PSTN and into an Ethernet and the cordless handset works with both Skype and the landline.

What was really impressive was the simplicity of setup: I plugged the basestation into our LAN and it got an IP address from our DHCP server without prompting. I then entered my wife’s Skype ID and Password and, co-incidently, our son in Australia (15870 km in the other direction) decided to call us on Skype. The telephone rang, much to our surprise; Alison answered it and was talking.

What was also nice was that, since Skype stores contact identities at the server rather than at the telephone, all of her contacts were immediately available on the new telephone. I wonder why landline carriers don’t do this.

So, the two advantages have now dropped to one: emergency service. I have that available on my cellular telephone so what is preventing me from getting rid of my landline?

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1 Response to "Telephony"

You mention that hearing things before seeing them is a new phenomenon; I am in the habit of watching Welsh rugby broadcast on S4C Digital, a Welsh-only station, with the sound muted, while listening to commentary on analogue radio. I am now used to hearing the referee’s whistle preceeding the stoppage of play by anything up to 2 seconds…

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Disclaimer

The author of this blog used to be an employee of Nortel. Even when he worked for Nortel the views expressed in the blog did not represent the views of Nortel. Now that he has left, the chances are even smaller that his views match those of Nortel.
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