trouble with alarm clock function

I recently got the samsung after my older motorola fell apart. Jusst for the heck of it, I decided to switch to the samsung brand, but I know found myself lost and confused.

With my old phone, my alarm clock would ring (or vibrate) until I gave it some kind of input (so until I opened it, closed it, or turned it off) it would vibrate indefinitely, even 30 minutes at an end if I ended up sleeping in.

Much to my alarm (no pun intended) I discovered this morning, after I overslept, that the Rugby's alarm will go off for about a minute or two, and then just stop, as if it were assuming that I didn't want to get up. On my commute to work, I ran some mock alarm tests, and during a certain test, after the alarm finished ringing, it automatically entered snooze mode, with no input on my part. However, I haven't gotten my Rugby to do it again. I tried activating and deactivating my snooze feature, but I cannot get my phone to vibe ring indefinitely.

Can anybody please tell me how I can make my phone's built in alarm ring until I tell it to stop?