When you are out of network range or the phone is switched off, you will receive an SMS notification of all missed calls.
What's Missed Call Alert ?
How Does It Work?
When your phone is
out of network coverage area or is switched off,
you will receive a notification SMS of any missed calls
once your phone is switched on. You will not be charged for
the notification SMS received.

“My phone is usually off when I am in meetings or traveling, but I don’t want to miss any important calls. With Missed Call Alert , I am always notified when someone wants to connect with me!”