I designed the ISP business model
In the early days of the Internet there was a wise debate about how to divide the costs and income across a connection.
The answer was that is no single "fair" system! I proposed that every ISP pays for their network and collects from their customers. I.e. no "settlement". This idea won on the basis that it was cheap to implement (no accounting) and meant there were no need for complicated legal agreements to sort out the money.
Neutral interconnects such as MaeEast and LINX meant that the cost of the interconnection was minimal, and sort of fair.
Ever since various parties, especially Telcos have tried to change the rules, in ways that consistently benefit themselves, ( who would guess)
To repeat, There is NO SINGLE FAIR SYSTEM for inter ISP settlement! The NULL system is cheap and easy!
Peter Dawe
Founder Unipalm, PIPEX, LINX, ISPA IWF ...