In telecommunication, the term overflow has the following meanings:
1. In telephony, the generation of potential traffic that exceeds the capacity of a communications system or subsystem.
2. In telephony, a count of telephone call attempts made on groups of busy trunks or access lines.
3. In telephony, traffic handled by overflow equipment.
4. In telephony, traffic that exceeds the capacity of the switching equipment and is therefore lost.
5. In telephony, on a particular route, excess traffic that is offered to another route, i.e. , an alternate route.
6. In digital computing, synonym for arithmetic overflow. 7. In digital communications, the condition that exists when the incoming data rate exceeds that which can be accommodated by a buffer, resulting in the loss of information.
Source: from Federal Standard 1037C and from MIL-STD-188