gōng​gòng​jiāo​huàn​diàn​huà​wǎng

public switched telephone network

  1. public
    belonging to or shared by the whole community; common; communal
  2. commutative
    (math) relating to the property where the order of operations does not change the result; (telecom) to switch signals or connections
  3. telephone network
    a system of interconnected telephone lines or technology