It might be a telemarketer. If you call the number and it is busy or goes weird, that's likely the case.

But if someone keeps hanging up - like you can hear a real person doing that - or even if you can't - also call your phone service provider about it.

I couldn't find any matches on it.

HEY - I'd forgotten about this, I just found it! "Toll-free directory assistance for some toll-free numbers can be obtained by calling 1-800-555-1212"

It's a free call.