International telecommunications is an infrastructure of agreements and connections between different communications companies in different states and countries around the world. They make it possible for anyone to call or connect to almost anywhere on the globe from the comfort of his or her own home. This infrastructure might be Voice over Internet Protocol (VoIP), telephone, satellite, cell phone, or a combination of all four; the term international telecommunications covers them all.
There are hundreds, if not thousands, of telecommunications companies throughout the world, all of whom offer different services to their customers. Not all of them are big enough to have their own cables or fibers going across their territory, so they have agreements in place whereby they "rent" space on another carrier's network to carry calls. This rental is much like a consumer cell phone plan, where the contract includes so many minutes per month in the fee. The companies will buy an allocation of so many minutes per day, week, month, or year from other carriers, then pay so much money per minute thereafter.
A long distance, or international, call might use several other companies' networks in its journey. They all incur a charge for the telecommunications company, which is passed on to the consumer; this is part of why long distance or international calls are more expensive than local calls. The number of minutes a carrier buys from another carrier is called the wholesale rate. This is much lower than the consumer rate, so each company can make a profit carrying the calls.
For example, a call from New York to London will use a local carrier, a transatlantic carrier, then another local carrier at the far end. The call will begin with the local carrier, whose telephone switch will recognize the numbers dialed as international. It will route it to an interconnect with their international telecommunications carrier of choice, who will send the call to the United Kingdom.
In the UK, the call will be picked up by the international carrier's company of choice, then routed to the destination. The person making the call will be billed for the whole call. The local carrier will be billed for the call from the international telecommunications company to the destination, and the international carrier will be billed from the destination carrier. Each will incur a small cost to carry the call over their own network.
International telecommunications is a virtual web connecting the majority of the world. This web is comprised of individual companies who agree to carry each other's calls as part of this web, providing a seamless service to the consumer. All of the connections are already in place and are programmed to occur automatically, which enables the calls to be connected almost instantaneously.