....to persistently ignore....

[SnapFrakkleAndPop]

....calls from a company trying to sell me something in the hope they'll give up?

They've called me 5 times so far today, left 2 messages and are generally annoying me. I don't want to call them up because then I'll be trapped on the phone for ages. They didn't accept 'I don't want to buy this product' and told me that they'd call back today once I'd had time to think about it.

I just hang up. I got fed up with being polite. Another thing that works well is to say "hello, hello?" repeatedly as if you can't hear anything and then hang up.

Answer the phone ask them to hold then go about your daily stuff while they sit waiting for you to come back

I think you need to man up a bit. Why would you be trapped on the phone. Say " no, and don't call this number again" and hang up, its that simple.

I used to give the phone to ds when he was at the stage when he couldn't talk. He'd breathe down the phone instead..........they'd usually hang up pretty quickly