How much of Nashville TN had this off hook tone

  How much of Nashville TN had this off hook tone? They had ATT/Philps Tel 5ESS-PBX Host Switches with a lot of Tennessee Telephone Company Inc. offices. So how much of Nashville TN had this off hook tone? I still wanna know what kind of off hook tone this is and what the technical name for this off hook tone is, Please let me know. Thank you.