open line 
noun
A telephone line on which conversations can be overheard or intercepted by others.‘We had to open lines of communication and lines of supply in places where we did not necessarily want to put boots on the ground,’ Capt. Homes explained....
- He began by holding up his mobile phone saying, ‘This telephone has an open line to a refugee camp in the Gaza Strip.’
- She establishes open lines of communication and an atmosphere of mutual respect among all members of her surgical team.
adjective Canadian
Denoting a phone-in radio or television programme.After a few years running an open-line radio show, Kiviaq entered law school....
- One caller to an open-line radio show quipped: ‘Ralph can run the country half-drunk better than the other people we have in charge.’
- ‘Newspapers were denouncing me, open-line shows too, and people were phoning me up and threatening me, but a few MPs gave me support, as did the Commissioner of Official Languages,’ Thibodeau says.