Sharp FO-2600 Service Manual page 29

$W28 No. 4, No. 5 Ringer volume (SG/GH only)
Used to adjust ringer volume. (3phase)
00: Low
01; Middle
10: High
SW28 No. 6 ~ No. 8 Reserved (SG/GH only)
Set to "0°.
$W29 No. 1 ~ No. 4 DTMF signal transmission leve! of higher
frequency (dBm) (SG/GH only)
The transmission level of DTMF signal is adjusted. (higher frequency)
0000: 0dBm
4
1411; -15dBm
SW29 No. 5 ~ No. 8 DTMF signal transmission level of lower
frequency (dBm) (SG/GH only)
The transmission level of DTMF signat is adjusted. (lower frequency)
0000: dBm
4
11414: -15dBm,
2~19
FO-2600TH/SG
FO-2600GU/GH