Android 2.3 set call volume

i tried quite all the options but i can't find the solution. I already have the volume at maximum when i press the + button during a call. The phone hadn't this behaviour when i first used it (it is a ZTE-blade). Maybe(i'm not sure) this started after flashing it with cyanogenmod 7.1 (before it had ginger stir fry) Is there an option to turn it up? i have a really hard time trying to hear what people says on calls..