Title: Define POTS, DID, OPX, tie-lines, and WATS lines.
Course: Telecommunications I (10006-I) > Section: Exploring Analog Telephony and Transmission Service Providers

Definition should include the following abbreviations and terms:

- POTS (plain old telephone service)—a voice-grade telephone service based on analog signal transmission
- DID (direct inward dialing)—allows an individual extension on a private branch exchange (PBX) to be reached directly via its own standard outside number, determining the appropriate situations to use each service
- OPX (off-premise extension)—an extension telephone at a location distant from its servicing PBX
- tie-line—a telephone line that directly connects two or more PBXs
- WATS (wide area telephone service)—flat-rate long-distance service offering for customer dial-type telecommunications

Process/Skill Questions:

- What was the voice-grade telephone service based on analog signal transmission that was common before the advent of advanced forms of telephony?
- When would you use OPX?
- How does WATS work?