Calling Line Identifier

CMX602B

 2003 CML Microsystems Plc

11

D/602B/2

applications, the longer (88 to 110ms) Tone Alert signal employed by BT for on-hook applications will not

necessarily cause IRQN to go low.

See section 1.7.1 for definitions of Tton, Ttoff and TqCAS

Figure 6 : Tone Alert Detector operation

1.5.8

Ring or Line Polarity Reversal Detector

These circuits are used to detect the Line Polarity Reversal and Ringing signals associated with the Calling

Line Identification protocol.

Figure 7 illustrates their use in a typical application.

Figure 7 : Ring or Line Polarity Reversal operation