| Answer | Crossword Clue |
|---|---|
| EXT | Phone-system abbr. |
| TIELINE | Phone-system connection |
| LINEONE | Phone system starting point |
| MENU | Automated phone-system component |
| TWOGNETWORK | Mobile phone system that introduced SMS texting |
| callbacks | A security feature used by systems accessed by telephone, in which a remote user must log on using a previously registered phone number, to which the system then places a return call |
