ISDN TA POTS Interface

CMX625

 2001 Consumer Microcircuits Limited

23

D/625/2

1.6

Application Notes

Figure 10 Tone Starting and Stopping

When switching between tones in the same column (bits 4 - 7 or bits 0 - 3) of the TX TONES

Register), the transition will be phase continuous. However, switching to the ‘OFF’ state will

Figure 11 Tone Changing

The TX TONES Register which does not have a frequency allocated is indicated by ‘-’ in the Tone

Field tables. These values should not be used.

1.6.1

Telecom Tones

The following tables give the hex codes to be programmed into the particular tone field location for

various telecommunications systems applications. The tables are not exhaustive, but list the more

commonly used tones.

Ringing Signals

(f ±2.5%)

Field 0

(Hz)

(Hex)

Off

$00

16.7

$01

20

$02

25

$03

35

$04

40

$05

50

$06