Who called from 2312242015

Someone is calling my personal cell phone, and hang ups when I answer. I don't answer anymore, and the caller doesn't leave messages. I hope it's nothing important.

Recieved a call from 1-231-224-2015 @ 2:06 am.
Woke my handicapped wife from a sound sleep.
When she answered, caller hung up.

455am received a called from 231 224 2015  person doesn't say anything and hung up

Received a call at 5:01 a.m. from this number hung up when answering maching started.

At 2:45 A.M.last night a call came in from this number and of course you expect the worst.  No one said anything when I answered,they just hung up. Good luck getting back to sleep.