Ricoh Aficio MP C3001 Service Manual page 1936

Bit Switches
PSTN cable equalizer
(V.8/V.17 rx mode: External)
4
0: Disabled
1: Enabled
5-7 Not used
G3-2 Switch 08 - Not used (do not change the settings)
G3-2 Switch 09 - Not used (do not change the settings)
D545
Keep this bit at "1".
Do not change the settings.
132 SM