If it is the Royal Institute for the Deaf and Blind, maybe it's about time being on the Do Not Call Register also included charities and all call centres. It's a waste of the charities' money when the answering machine picks up as then they're being charged for the call. Surely they don't get a lot of donations by really annoying people?

Hi to anyone interested.
When I receive calls from unknown numbers, I ignore them.
I called the number back. (02) 8916 8021, message says:
"Thank you for calling the Royal Institute for the Deaf and Blind"

Calls at regular intervals on my mobile. No message left.

Frequently calls mobile. Muffled voice if answered. If dial back says recorded message says previously Institute for Deaf and Blind.

Caller: (02) 8916 8021

Just hung up when I answered

Didn't answer - no message left

Same as all the previous comments. I don't pick up when I see a number I don't recognise. Surely the number is registered to someone - so why don't the details come up when you do a number search? Seems to be something the regulators need to look at?

It rang 3 times not long and no voicemail...

Same as everyone else. Called on the landline, picked up by answering machine - didn't leave a message so no idea who they are.

I let it ring out, no message was left

Same thing happened to me - as soon as the answering machine picked up, they hung up. And all these people wonder why you don't answer.

I let it ring out and they didn’t leave a message