Class of call discriminating trunk circuit

摘要

A communication system is disclosed for providing itemized telephone subscriber billing of special assistance calls. A local office not equipped with automatic message accounting facilities is interconnected via a trunk circuit to another exchange having such facilities and thence to a special assistance bureau. The trunk circuit is accessible by the local office for both message rate billed and special assistance classes of traffic. On each call therethrough, the trunk circuit translates subscriber dialed digits for selecting the automatic accounting facilities or message rate billing apparatus in the local office in accordance with whether the call is of a special assistance or local toll call class as defined by the digits.