Think of who is "they" who is targeting the ads, and what "they" is collecting the data.
Telcos are not giving anything except the IP address. If you go to other websites and don't provide your data to them, all they will have is an identifier about the IP. It is that data that can be managed under GDPR, but IP in isolation means nothing.
Telcos are not giving anything except the IP address. If you go to other websites and don't provide your data to them, all they will have is an identifier about the IP. It is that data that can be managed under GDPR, but IP in isolation means nothing.