On March 5, 1919, cartoonist W.K. Haselden published a comic in the British newspaper The Mirror, illustrating what the world would be like if telephones were portable.
This is alright to a point but it's not always spam.
Like when you've applied for a rental property, or a job, or whatever. At that point the phone calls need to be answered.
Because it isn't always spam. I get calls about work regularly and my phone # is posted online and I get maybe 1 spam call a week. The rest are legit. In my business, we only call people when it's time sensitive, so if the phone rings it needs an answer.
It's just childish to ignore all phone calls. Especially from those in your contact list
I get at least two spam calls a day so, outside of calls from my contact list, I ignore everything. If it's an important and time sensitive thing, they need to leave me a message because cold calls from random strings of numbers don't get returned.