Abstract: Redundant but independently operable data processors called encoders are arranged so that control of a particular recorder gathering billing data in a telephone switching system can be transferred while maintaining billing continuity for calls being handled by that recorder. More specifically, each encoder checks the validity of billing information received from each recorder. However, each encoder only transmits billing data pertaining to a designated group of recorders to a remote processor. When an encoder detects that it is not receiving valid data from one of its designated recorders, the control of only that designated recorder is transferred to the other encoder if the other encoder indicates that it is receiving valid data from that recorder.

Abstract: A timing arrangement for use with a telephone switching system equipped with automatic message accounting equipment to adjust call charging times to compensate for delays in obtaining access to the automatic message accounting equipment. Timing circuitry provided in an automatic message accounting recorder measures the period of time since the recorder was last idle with no call carrying trunks of the switching system waiting to be serviced by the recorder. Apparatus enabled by the timing circuitry generates an allowance time used to adjust a registered trunk call charging time in accordance with the trunk access delay to the automatic message accounting equipment.