I have the same exctact problem with my Sprint Curve. I also have a Tmob Curve and it's volume is easily 30%-40% louder on speaker and with bluetooth. What's that all about?
__________________ T-Mobile Blackberry Curve 8320 Titanium
[Unlocked, OS: BB 8320 4.5.18, 4 GB SD Card] Sprint Blackberry Curve 8330
[2GB SD Card]