Abstract: A digital line card for interfacing a remotely located digital telephone to a central office system by a two-wire connection is disclosed. The digital line card consists of a line interface connected to the two-wire connection. The line interface provides a full duplex transmission link with the remotely located digital telephone over the two-wire connection. A buffer is connected between the line interface and the central office system. The buffer converts data between the line interface and the central office system. The line card further comprising a protocol controller connected to the line interface. The protocol controller performs a packet protocol for communications with the remotely located telephone.

Abstract: A digital test card for testing the quality of a digital system in a central office system is disclosed. Where the digital system consists of a digital line card connected to a customer premise equipment by a two-wire connection. The digital test card comprises a line interface which provides a full duplex transmission link. When the digital test card is testing the customer premises equipment the line interface operates as a master; when testing the digital line card the line interface operates as a slave. There is also a relay for connecting the line interface to the customer premise equipment or the digital line card. Connected between the line interface and the central office system is a buffer. A protocol controller connected to the line interface performs a packet protocol. And finally there is a processor. Under the direction of the central office system, the processor controls the operation of the digital line card and determines the quality of the digital system.

Abstract: A method is disclosed for distributing operating program data stored in a common memory area of a digital telephone system, to a plurality of digital telephone system controllers. The method includes transmitting the operating program data from the common memory via a control/data bus to remotely located digital facility test card. The digital facility test card receives and stores a load image of the operating program in random access memory (RAM). A PCM network connection is established from the digital facility test card to each of the plurality of digital telephone controllers through the digital telephone system. The stored load image from the digital facility test card RAM is then transmitted to each of the digital telephone system controllers via the PCM network connection.

Abstract: A circuit for dividing a clock signal by two and one-half (2.5) is shown. The divide by two and one-half (2.5) circuit includes a clock selector circuit arranged to output a selected polarity of the first clock signal. A ring counter arranged to receive the clock selector circuit output signal, and output a signal that has a period of 3 times (3.times.) the signal received from the clock selector circuit. A divide by two circuit connected to the ring counter circuit and to the clock selector circuit. The divide by two circuit divides the ring counter output signal by two to produce an output signal. The divide by two output signal is then fed back to the clock selector circuit to regulate the selection of the first clock signal polarity, causing the ring counter to output a clock signal with a period of two and one-half times (2.5.times.) the first clock signal.