Bandwidth provision is a pretty complex offering, so it's hard to say really. MTN's network is owned by themselves, but where traffic is routed into their network and out of their network they have to pay upstream fees or licences to those service providers. So for example, traffic from your router going over to, say, a Google server in the UK. Afrihost and MTN have to pay Telkom for the traffic that breaks out of their network onto MTN's national fibre network (which is called IP Connect) and is then routed to our international breakout point over an undersea cable. MTN then pays an international cable link provider (like WACS or EASSy) for capacity on their links to be able to route traffic via their cable to the UK network. It is then received by an international partner network or CDN (like Level 3) where traffic is routed to the content seving host network.
Even this is a fairly simple breakdown and not the most complex scenario. But there is basically a long chain of networks and routing which makes the internet work and a lot of upstream costs and agreements which allow us to connect to it all.
Hope that helps :)
PS ICANN is an international domain registration authority, think of it as a regulatory body for domain registrars like ISPA is a regulatory body for South African ISPs.