Judging from the caller ID it looks like a spoofed number.
2010-03-05 17:08:08 "12345678915" <12345678915> s NO ANSWER 00:11
2010-03-05 17:06:56 "12345678915" <12345678915> s NO ANSWER 00:18
2010-03-05 11:08:21 "12504128815" <12504128815> s NO ANSWER 00:30