Definitions of common carrier
a company that transports goods or passengers on regular routes at agreed rates and which must treat all customers equally, unlike private carriers which may refuse customers
It is clear that the Commission had the discretion to require the service provider to serve all potential customers indifferently, thus making them common carriers.
a telephone company
The Federal Communications Commission had tried to impose so-called "common carrier" regulations on broadband providers without officially classifying them as utilities.