There's the led indicator you can check immediately if there are new notifications
As per SMS vs Email, for me the importance is not the same in the first place, since I don't receive SMSs from random people or a guy called BugZilla , It's very annoyed to get beeps every minute, very distracting, but I'm talking here about my personal view on the issue, please note I'm not a UX person so I don't decide in such behaviors anyway, but thanks for the feedback.