 Region number × 20

Then when some regions started running out of network numbers, the following was also used.Region number × 200

Region 19, for instance, contains nets 380-399 and 3800-3999 in addition to those that were in Region 19 when it was formed.Part of the objective behind the formation of local nets was to implement cost reduction plans by which all messages would be sent to one or more hubs or hosts in compressed form (ARC was nominally standard, but PKZIP is universally supported); one toll call could then be made during off-peak hours to exchange entire message-filled archives with an out-of-town uplink for further redistribution.