teleblock questions

I just had a call that rang 3 times and then disconnected, CID said "telemarketer" and the number, 615 a/c is all I remember. Control panel doesn't show it in the history, so I'm wondering if it might have been submitted by someone to the teleblock list and then dropped by the system, or maybe the caller only rang 3 times and hung up.

What happens to numbers users submit?

Telemarketers' predictive dialers are famous for hanging up after a few rings - perhaps because there were no free agents in the call center to take the call even if you answered.