Thinking about it, I *only* get unknown calls from weird numbers from Jamaica and 08 numbers which I don't trust.

If it were a mobile number I didn't recognise though, I'd probably answer unless I am unable to do so. Such as being at work! 2-3 hours straight that I am unable to check my phone. xD Leaving messages is pretty much the only guaranteed way to get a hold of me.

I don't get calls from other mobile numbers or even 01 or 02 numbers so I guess it doesn't really make too much difference for me.