Blocking unwanted calls

Good morning,

I know we can block unwanted numbers. But the call centers have found a trick to get around the blockage.

They call each other anonymously and no blocking is possible because you need a number. But does Swisscom have a solution because we are harassed several times a day and what to do. Please give me a solution if possible. Thanks in advance

Good morning,

I have known this for a long time and practice it often. But when the call shows ANONYMOUS we cannot block it and I wanted to know if Swisscom can do anything.