What is the intrinsic sense in which telephony is a utility but social media isn't? The wires? Phone companies all share the wires now (thanks again to government regulation), and with VoIP it's becoming less relevant by the day.. but phone number porting still works fine. The physical infrastructure natural monopoly stuff isn't a necessary component of what makes government regulation of phone systems work out well.
The government regulation of the phone system works well because the government regulations are well designed, not because there's a limit to how many wires you can hang from a pole.
The government regulation of the phone system works well because the government regulations are well designed, not because there's a limit to how many wires you can hang from a pole.