My business partner with a Pearl 8130 left about 10 minutes before my last post, so I couldn't look at his. Does the Pearl not have up/down volume buttons on the side?
Also in the Phone app (press green SEND button or Phone icon), press MENU aka BB button and select Options, then General Options, and see if there's a spot to select Default Call Volume. Set it to 100%. My menu options might be labelled slightly diferently so poke around a bit.
Posted from my CrackBerry at wapforums.crackberry.com