Yea, i was deleting numbers to make room for more numbers to block. Got fed up with it now and brought a new phone which blocks all unwanted calls 100%. Don't get any now, peace on earth
The scammers now change their numbers all the time in order to make the blacklists pretty much useless. As you say, it's hard to know which ones to delete as numbers do come back again from months ago!
People are now moving to the call blocking phones which do cost of course and need to be set up and monitored.
In my case where I look after my mum's phone from 250 miles away, I opted to use the Do Not Disturb and VIP List part of the Call Protect system. It does cost £3.50 per month, but works very well - worth the peace of mind I think.
For this I have set her phone to send ALL calls to voicemail every day, 24 hours, (ie 24/7!) and only allow numbers in her VIP List to actually ring the phone. This list is friends, family, doctors, services. I can monitor and add to this list myself. The only thing I can't do is hear the calls on voicemail, but I do check the numbers most days using Google, and it's clear that all the calls so far have been scammers.
So far it has stopped 757 calls to her phone ... big success ... as you can see!
I have been monitoring and logging my mum's scammer activity ... over the last 35 weeks, this is how her daily calls stack up.
Maybe this will be of interest to someone!