Cryptonomicon

by Neal Stephenson

Callback and Kallback are registered trademarks of Seattle-based International Telcom Ltd. (ITL), but, like Band-aid and Kleenex, tend to be used in a generic way by people overseas. The callback concept is based on the fact that it’s much cheaper to call Japan from the US than it is to call the US from Japan. Subscribers to a callback service are given a phone number in the US. When they want to make a call, they dial that number, wait for it to ring once, and then hang up so they won’t be charged for the call. In the jargon of the callback world, this is the trigger call. A system in the US then calls them back, giving them a cheap international line, and once that is accomplished, it’s an easy matter to shunt the call elsewhere: to a number in the States or in any other country in the world. Any phone call made between two countries is subject to a so-called settlement charge, which is assessed on a per-minute basis. The amount of the settlement charged is fixed by an agreement between the two countries’ PTTs and generally provides a barometer of their relative size and power. So, for example, when working out the deal with Denmark, Pakistan might say, “Hey, Danes are rich, and we don’t really care whether they call us or not, and they have no particular leverage over us — so POW!” and insist on a high settlement charge — say $4 per minute. But when negotiating against AT&T, Pakistan might agree to a lower settlement charge — say $1 per minute. Settlement charges have l...