caller never answers then disconnects

Phone rang only once. Caller hung up when I picked up the phone to answer.

Left me an indistinguishable message at 4:00 in the morning.

Once I answered the phone, the caller had disconected.

my friend calls me from the UK on a calling card and this is one of the numbers that shows up.

I have received several calls from this number.  Answered once, and there was no conncetion.  I've even tried calling back a few times, but it just rings.

Two calls came in back to back at 9:15 pm and 9:21 pm. First was from 692-563-7551 and second was from 722-563-7551. Both were answered but no connection. Was expecting international call from my husband which did come a minute after the second call. Caller ID listed his call with his normal international phone number.