If you're thinking of operating in the USA, you should read up on Communications Assistance for Law Enforcement (CALEA). CALEA pretty much requires that you be

If you're thinking of operating in the USA, you should read up on Communications Assistance for Law Enforcement (CALEA). CALEA pretty much requires that you be able to associate a name with any IP on your network, so you're going to have a hard time operating as an ISP without any personally-identifying information about your customers. Regardless, if you can figure out a way to anonymously collect payment for services online without either getting ripped off by your own customers or leaving a paper trail for law enforcement to subpoena, then you have a far more valuable commodity than simple bandwidth to offer. In fact, you would have invented "digital cash", and any number of folks (afore-mentioned law enforcement and tax agencies amongst them) will race each other to control or use it.