Reverse look up on this country code (234) indicates it is from Nigeria. I did not answer these call as they were in the middle of the night. However they called back several times, in groups of 2 calls. Example they would call at 12:34am and it would ring until they received a message indicating that I was not available and then it would call back immediately. Then I would get the call again 30-45 minutes later. Strange.

Does anyone have any information on this?