Theirs and also stifling competition. If ATT has not been broken up Cell phone technology would have been another 20 years down the road. ATT was a controlling public Monopoly , look up the court case. When ATT was finally broken up, there was an explosion in technology advancement especially in Cell Phones.
Cell phone technology? ATT was not broken up to enable cellphone technology. It was broken up in a ham-fisted government shakedown. Any alleged benefits to innocent 3rd parties is entirely accidental, insignificant in comparison to the value destroyed.
Cell phone technology? God forbid we should not have cellphone technology.