[mrailing]

Voice Command is turned on to read messages. Click Start-Settings-All Settings (left soft key), "Personal" tab. Voice Command. Select "messaging" and then click "notifications. Change it to "Announce notifications using Bluetooth Hands Free Only, and it will only read when you have a headset.

If you don't want it to announce at all, just uncheck it from the main list, but I find it nice with a headset in...