Urmet 1+1 doorphone circuit understanding

Hi everybody, I'm new here and hopefully will become a regular member here soon I'm stugling with understanding how my doorphone works. As I became a father few days ago I wanted to be able to switch the ringing off with a switch but as there are only two wires, I have to say that I'm confused how it could be accomplished. The doorphone is connected to s main station at the bottom of our building that has 46/47 flats. Indoor unit has these possibilities:
- open the door lock
- talk with someone in front of the main unit
- ring from main unit
- ring from the flat's door switch (this has a slightly different ringing)

Anyway, here are fewphotos I took of the indoor unit and it's wiring..

Can somebody explan how this unit works? How it distinguishesh two different rings (outside/indoor)? And, hopefully, where should i put a switch?

Here are the pics...

From looking at the photos, the "ringer" is in the phone. If you switch off the ringer then you don't know when some one is phoning you, so might as unplug the phone. If its a modern phone the ringer is actually an oscillator that fire up the earpiece.
Frank

I opened the phone also, but there are only two things and 4 wires - a mic and a speaker

By the way, the doorphone I'm referring to in this thread is Urmet 1133 Atlantico, if this might help...

Frank, you think that oscilator is somewhere inside the speaker itself?

suntribe said:

Frank, you think that oscilator is somewhere inside the speaker itself?

Click to expand...

The phone does not appear to have an old fashioned "coil and gongs ringer". Does the ringing come from the speaker or from the earphone? If it does then it has an oscillator driving the speaker or earphone to make the ringing sound. To turn off the ringing then use a switch to turn off the oscillator, speaker or earphone that makes the sound.