I have noticed the volume in voicemail recordings is low; searching here, I have found that I can use the “g#” option. However, I can’t find how to use it with the “u” and “b” options - when I try to combine them (e.g. ug9, or g9u or g9,u), Asterisk dies.
Can they be used together? If not, how can I achieve the result I want?