There's no set limit to the number of messages that a BlackBerry can hold. BlackBerry devices are different from other devices. They don't have those hard set limits. The messages are stored along with the other device data in the device memory. The device can hold thousands of messages. You only need to keep a watch on your File Free.
In your message folder there is an option to set how long you save messages. I don't like to hold them any longer than 15 days are else it makes the phone lag and the reboots even longer than they need to be. Then again I'm working with a lot less memory on my Curve than your Tour.
