As cell and sim systems advanced the security services just kept up with having total mastery of every aspect of all the different telco networks.
Now users and telcos have to consider who else has the security services methods? Ex staff, former staff, dual citizens, contractors, foreign contractors. People cults and brands able to pay for the skill sets of ex staff, former staff? Once a telco network is fully open to the security services other groups can buy or are given the same methods over the years.