You guys are mistating the issue a bit.
There is no such thing as bandwidth.... let me explain.
You pay Telkom for a 384/512/1024Kbit pipe onto thier network, that is the badnwidth section. They have contention ratios of say 60:1 (no one knows exact values) i.e. they sell that same 384/512/1024Kbit 60 times.
It is thierfore irrelevant how much traffic you put over that link, as you're paying for the segment.
The only reason there are caps in place is because of Network Congestion, i.e. Telkom doesn't have enough bandwidth on thier network (remember by bandwidth I mean 155MBit lines) to sell 160 000 ADSL users 1MBit each, even at 60:1. So they need to limit the users usage of the lines in order to keep the network uncongested.
Capping is practiced on alot of networks internationally as well, because providers have to over sell to make profits.
My point being, Telkom doesn't buy GB's because there are no such thing as GB's it's simply a congestion game..
Yes, bandwidth as in the term I used means "bandwidth is the amount of information downloadable from the webserver over a prescribed period of time", however Telkom uses a per gig model in south africa to rent out the bandwidth they have available, as you are aware.
You are correct in Telkom having bandwidth available measured in the true sense in Mbit/Gigabit format rather than in a traffic basis.
Oh, and Telkom / SAIX / Telkominternet are not virtually the same company, they ARE the same company... Telkom SA Ltd.
I said they are basically the same company. However they wont admit they have the same VAT number. (SAIX, TelkomInternet, TelkomSA)