Yes once the phone has been slid open the keypay is unlocked, which only makes sense.. when will your phone ever be open in your pocket, plus you can unlock it with the power button on the top .

And for the alarm im pretty sure you can set it to either go off once or every 'x' amount of minutes. You can also activate a snooze as well

hope this helps

Can you tell me a bit about how the key locking on the U600 works? Does sliding open the phone automatically unlock the keypad? Also, does anyone use the alarm? Can someone tell me if the alarm turns itself off after having gone off for a while? My Samsung t509 turns off the alarm after about five minutes, and my body has caught on-- I'd like it to sound the alarm until I turn it off. Thanks in advance for any answers.