Pisses me off.
I never give my phone number out to companies when ordering stuff etc. I always put a false one in because they never actually need to contact me and if they do, they can email me or something.
The exceptions being John Lewis and recently IO.com (I'd ordered a Henry and they stated they would text me my delivery time)
Since then I've had 8 calls offering me various insurances and asking me if I've had accidents.