I called back number (07) 3547 7114 reached voice mail for a charity company but did not say the na.e

As previous commenters have said, this is from a number "calling on behalf of a charity you may have supported in the past, or sometimes we call people to see if they want to support the charity". Uggghhhhh. I've blocked them. The same people have also called me from a mobile number (sneaky) -- 0491 051 864. Blocked them there too! I'd been getting a call a day. So annoying.

rang but hang up when I went to pick up.

Have been getting calls from this number but if I answer it hangs up immediately. I call back and get a recorded message saying it’s from a charity and to email callingenquiries @ Protophone.com if I want the calls to stop. Don’t want them having my email as well so have blocked.