Yes, the surgery does display its number when calling or texting us re appointments such as mass Covid, flu vaccs etc. I think the doctors make pre-arranged individual calls to patients using number-withheld mobile to avoid being swamped with calls which should go through surgery triage. Genuine emergency calls are handled within minutes -- we can gratefully attest to that.

All they need to present is a number to be displayed which can then be whitelisted. It doesn't really matter whether that number is active in their system or can be called back but as mentioned, most companies use the main published number for this purpose.

To tell you frankly, changing the telephone number is the best solution!

I used to get lots of spam with my previous telephone line for years. When I switched to new ISP during my migration from Plusnet to TalkTalk 3 years ago I opted for new telephone number and never had spam calls since.

I then happily switched to BT 2 years later by preserving existing number since I was happy.

I had also tons of spam calls in my old 3 Network Pay as you Go phone. This all started after I had initially graduated Uni in 2012 when I started looking for jobs in Graphic Design, etc I publicly put my CV/Graphic Design Portfolio. Little did I know that this led to spam!

Instead of actually getting interested participants to ask me for job experience, I got life insurance surveys and accident help line phone calls. There was nothing I could do, block phone call and they come with another. I had 500 blocked phone calls in my phone and you know what? Even though the number may not show up, it did silently drain my battery life.

I abandoned 3 Network last year for the first time since having the same number from 2009. I switched to RWG and never had a spam call since. Now I don't publicly publish my CV/Portfolio online with the number. Keep all personal phone numbers and emails private!

This is a precaution. The same goes with my Hotmail, had spam there and till today I still get like 50 emails a day. I didn't delete it because I have Xbox/Games for Windows Live achievements as well as Skype.

I switched to a new primary emails like Yandex, Mailfence, GMX, etc and no single spam yet there since opening those in 2017! The best way to avoid spam is to prevent them from getting your number. I can assure you simply telling them to stop won't work! I have told many times to the spammers "stop calling me, I'm not interested"! "I've already done a survey with you". But they won't leave you at peace.

Somehow when your phone number or email gets spoofed, it's game over! You'll get spam forever and changing number and email is the only solution. But you need to make sure they don't get hold of those details again by having the numbers published.

There's also a setting in the ISP to check box for ex-directory "If a person or their phone number is ex-directory, the number is not listed in the telephone directory, and the phone company will not give it to people who ask for it."

Prevention is better than cure and this applies for phone and email spam as well, not just health!