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CMX602AP3

Calling Line Identifier plus Call Waiting (Type II)

CML Microsystems Plc 

Calling Line Identifier

CMX602A

1.6 Application Notes

1.6.1 'On-Hook' Operation

The systems described in this section operate when the telephone set is not in use (on-hook) to display the

number of a calling party before the call is answered.

British Telecom System

Figure 8a illustrates the line signalling and CMX602A I/O signals for the BT on-hook Calling Line ID system as

defined in BT specifications SIN227 and SIN242 part 1. A similar system is described in ETS 300 659-1 section

6.1.2c.

The Tone Alert signal consists of simultaneous 2130Hz and 2750Hz tones, the 'Chan Seize' signal is a '1010..'

FSK bit sequence. Not shown are the requirements for AC and DC loads, including a short initial Current

Wetting Pulse, to be applied to the line 20ms after the end of the Tone Alert signal and to be maintained during

reception of the FSK signal. Note that, for simplicity of presentation, the Data Retiming function is not used in

Figure 8a (RXCK is kept high).

Figure 8a : BT On-hook System Signals

Bellcore System

Figure 8b illustrates the line signalling and CMX602A I/O signals for the Bellcore on-hook Caller ID system as

defined in Bellcore documents GR-30-CORE and SR-TSV-002476 and also in ETS 300 659-1 section 6.1.1.

As for the BT system, the 'Chan Seize' signal is a '1010..' FSK bit sequence. The Bellcore specifications do not

require AC or DC line terminations while the FSK data is being received, however ETS 300 659-1 allows for the

possibility of an AC termination being applied. Note that, for simplicity of presentation, the Data Retiming

function is not used in Figure 8b (RXCK is kept high).

© 1998 Consumer Microcircuits Limited

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D/602A/4

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