I called back number (07) 3638 1503 reached voice mail for a charity company but did not say the name.

Called back and got this recorded message:
"Hi there - Thank you for your call. If you're calling to check on a missed call, then this is where it originated from. The call was made on behalf of a charity which you may support or have supported in the past. We also call people to see if they'd like to support. If you would no longer like to receive contact from us, please email us at:
callingenquiries @ paretophone.com.
This is an unattended message for your information; thank you and goodbye."

Hope that helps!

no one on line when I answered call on multiple occaisons. no answer when ring back

this number is from a charity organisation who calls to try to get you to donate to various causes

Declined the call, they left a voicemail where a man was blowing a raspberry then hung up. I assume this is a charity as they have been hounded by calls from so many in the last few weeks.