'Riiiiinnngggg' z_z

Its freaky when at two in the morning, the house phone suddenly rings for no apparent reason; and when I pick it up to answer and go hello, it goes dead. Possible explanations?

1) 'Ghost'. Doesn't seem right
2) Some one wants to check if anyone is home. Freaks me out a lot; for all I know, if I didn't answer it, a few men would have attempted to break in within the hour or something. Popular thief tactic.
3) Some circuit problem. Never heard of it before though, just pure speculation.
4) Some silly idiot called the wrong number, and in typical Malaysian fashion just cuts the phone straight off when realising it's the wrong person. Most comforting of all reasons, although the fact it happened in the early morning makes it... fishy.