RSPCA pet guide, I signed up on the website and they said they would ring to take my address for the free guide and (basically a sales pitch) to get donations, Which is fair enough and expected.
They were ringing to ask your postal address for a pet first aid guide (& try to get you to donate). I can understand why you can't just give them your address on the website. If you don't want to appear uncharitable and don't answer, They'll send you a text.