Don't you think they'd give up after certainly the second time?! I can understand somebody calling twice. Obviously these numbers never leave a message.
Nope, they won't. As long as they think they've got a chance to scam you, they'll keep going until they get a bite.
I had two callers this week claiming to be from BT Openreach. They've obviously cottoned on to the fact that you'll be suspicious if they say they're from BT (retail) and you happen to be with a different provider which is managing your account, but uses BT for the infrastructure. Unless you're in a cable area, the chances are that it's BT Openreach that manage the line to your home and I'd imagine that it's fairly easy to con people, especially as you see Openreach vans on a fairly regular basis.
The first call woke me up, but I was too groggy to deal with it and I just hung up. The second time was about an hour later and I was ready for it. I told the guy to go forth and multiply with himself and was instantly hit with a barrage of abuse; there's no way anyone who is genuinely from Openreach would behave like that!
I do wish these idiots would phone me in the afternoon when I'm more likely to be fully functional, but I suppose that's part of their scheme - catching people off-guard.