Re: Hello, my name is [Anglicised], I'm calling from [major corporation/department]
If I have time to spare, and/or I want to entertain my 10-year-old son, I'll adopt the Yuur Strategy, which can sometimes keep the conversation going for quite some time:
Hello, am I speaking with Mrs Hindle?
Yuur.
Hello Mrs Hindle, my name is Bob and I am calling from Optimise Your Energy Bills Limited.
Yuur.
Can I ask, do you currently have a Direct Debit with your energy provider?
Yuur.
And which energy provider are you with?
Yuur.
I'm sorry?
Yuur.
Did you say "Eon"?
Yuur.
And how much per month are you paying to Eon?
Yuur.
...it goes downhill eventually, but every second they spend is a second not spent talking to anyone gullible enough to fall for their scam.