Volunteer hobbyist ham radio operators are investigating the construction of an entirely radio-based world-wide network using TCP/IP.
Network 44, termed the AMPRNet, is that network.
An address allocation originally obtained in the 1970's by Hank Magnuski, today it is administered as a distributed disjoint group of subnets by regional "coordinators", who assign addresses on the network to ham radio operators in their area.
The worldwide overall organization of these subnetwork blocks is current handled by Brian Kantor.
Addresses on this network are available to any licensed amateur radio operator who is interested in advancing the art of ham radio digital communications. In most countries, there is a local coordinator who is responsible for assigning an address and updating the master hosts list. There is no formal organization, no membership requirements, and no dues. All of the work is done by volunteers as they have time to do it.
Internet connectivity and the management and behaviour of the connected host system is the responsibility of the person who owns that computer.
If you are a ham who needs an address, contact your local coordinator.
Hams are in an unusual situation compared to the rest of the Internet. We're trying to build our own radio-based network, so for the goals of the network, radio connectivity is more important than internet connectivity. The current structure of the AMPRNet is that there are a bunch of fully- and partially-isolated ("disjoint") subnets in nearly every country and most major cities around the world.
Some of these have radio links to adjacent subnets but no other connections, some of them are completely isolated, and some are connected to others via "tunnels" through the Internet. This is a network in growth, and the status of subnets changes daily.
There is a single low-bandwidth tunnelling router located at UCSD and managed by Brian Kantor. which allows a minimal connectivity between the main Internet and some parts of the AMPRNet. It is there primarily to allow experimenters on the AMPRNet the opportunity to exchange information and to obtain access to Internet resources.
AMPRNet is not intended to be, and should not be used as, a substitute for buying access to the Internet from a local Internet Service Provider. It is, at this point in its evolution, an experimental network which should not be relied upon to provide consistent or dependable communications. As with ham radio itself, it is a hobbyist adventure.