Telephone Exchanges around Knoxville TN

I've only seen 2 Telephone Exchanges around Knoxville TN with ATT/Philps Tel 5ESS-PBX Host switches. Concord did have this off hook tone. But did Halls? What other phone companies had this off hook tone? I still wanna know what kind of off hook tone this was and what the Technical name for this off hook tone is Please let me know. Thank you.