Answer:
PSTN
Step-by-step explanation:
The full form of PSTN is Public Switched Telephone Network. It is a traditional circuit-switched telephone network which is used by the several regional, local or national telephony operators. They came in used in 1800s. It is a form of communication among the people which works with the help of underground copper wires.
In the context, when I am travelling through the metropolitan as well as the rural areas of the North America, the PSTN provides the internet connectivity in all the places. It helps me to communicate with the other people with the help of a telephone.