I think its some type of generic number when people use a calling card. My friend (who doesn't have a cell or long distance on house phone) left a message on my voicemail following the missed calls from this number
I've recieved calls from this number on and off for months now, about one every three weeks to a month. Never leaves a message and number is always disconnected when I try to call them. I never had this problem till I changed my cell phone number with T-mobile. Within the first week I recieved the first one. The number will sometimes wait for the mail box sometimes it'll only ring once or twice.