Who called from 3100022588

This number called, but I didn't answer.  No message left.

Just got a call from these fools. 002 prefix?!? Really? Obviously like Kara, I didn't answer.

I said "hullo" three times to static; then a mechanical voice said "good-bye".

Is it possible that such calls are machinery designed to detect whether a human answers, so they can sell the number to telemarketers at a premium?

This number called, but I didn't answer.  message left but only static.

I answered...they hung up!!