Obviously a wrong number.  But, they left a message at about 7 am.  I will have to return their call between 2 and 3 am tomorrow.

There are two problems with that.  If they spoofed the number of an innocent party, you will end up harassing someone who has nothing to do with the call you received.  Even if you get through to whomever called you, if they are overseas, then it is daytime over there, so your 2 am would be 2 pm to them.