The telescreens in 1984 were two-way, it was mentioned in the scene with the exercise instructor :
"‘Smith!’ screamed the shrewish voice from the telescreen. ‘6079 Smith W.! Yes, YOU! Bend lower, please! You can do better than that. You’re not trying. Lower, please! THAT’S better, comrade. Now stand at ease, the whole squad, and watch me.’
A sudden hot sweat had broken out all over Winston’s body. His face remained completely inscrutable. Never show dismay! Never show resentment!"
"‘Smith!’ screamed the shrewish voice from the telescreen. ‘6079 Smith W.! Yes, YOU! Bend lower, please! You can do better than that. You’re not trying. Lower, please! THAT’S better, comrade. Now stand at ease, the whole squad, and watch me.’
A sudden hot sweat had broken out all over Winston’s body. His face remained completely inscrutable. Never show dismay! Never show resentment!"