
The most recent Computer Weekly indicated that over half of medium sized companies now have VOIP switches in place, which means that they could be connecting direct to each other, bypassing the traditional phone companies entirely. So I decided to plug a few figures into a spreadsheet and see how much it actually costs to make those calls, based on bandwidth prices alone. In order to keep things simple I checked a decent broadband provider (Zen) and noted that they charged £1.27 per GB of traffic.
Doing a bit of maths:
A)pence/Gigabyte = 127
B)kilobits/Gigabyte = 8,000,000 (close enough)
C)kilobits/penny = B/A = 63,000
D)kilobits/second = 20 (for a reasonable VOIP call)
E)seconds/penny = C/D = 3,150
F)minutes/penny = E/60 = 52
So, providing you're not paying for the actual call connection at the other end you can get nearly an hour of phone calls for a penny, anywhere in the world. Not bad at all. Of course, this relies on everyone running their own VOIP servers - but those seem to be coming down in price reasonably quickly, especially with Asterix and the like providing open source competition. The only thing that provides real complexity is the routing tables that convert from phone numbers to IP addresses - so far as I know those are all currently centralised. Unless we all just move over to using SIP addresses, which may take some time. Of course, the number of phone numbers I actually _know_ as opposed to pulling from an electronic address book is vanishingly small.