You can do volume settings in this page.

Parameter DBID_INVOICE_NUM
Description It configures the sending volume of the handset.
Permitted Values Integer from 0 to 9
Default 5
Web UI FXS > Preferences > Volume Settings > Handset Input Gain
Parameter DBID_OUTVOICE_NUM
Description It configures the handset’s volume level during a call.
Permitted Values Integer from 0 to 9
Default 5
Web UI FXS > Preferences > Volume Settings > Handset Volume
Parameter DBID_DTMF_VOLUME
Description It configures the volume of the DTMF tone (in dB).
Permitted Values Integer from 0 to 45
Default -19
Web UI FXS > Preferences > Volume Settings > DTMF Volume (0~-45)
Author：admin  Create time：2023-11-24 16:09
Last editor：admin  Update time：2024-01-03 16:20