A1 is regular common
A4 is probably meant for audio common. Regular common is usually return for ring and unlock signals. Audio common is return path for mic and speaker. These commons are separate so as to not have noise from ring/unlock show up on mic/speaker. But in many systems audio common is either not present or is just shorted with regular common. A1 and A4 are the same for Ring Intercom because when I use a multi-meter on them they seem to be connected together.
I did think that was the case. Thank you. May I ask if you do know, which of those wires (if any) would determine if the app shows the unlock door button. I have the Videx 3171p and the button is missing, I can unlock the door when someone buzzes and it “rings” via the app.
I don’t think this can be changed by wiring. The question is whether you can unlock your door using your own handset without somebody giving you a ring? If yes, then you can ask the CS that your system doesn’t need a ring and they should be able to change it. I know one person in this community who got it done this way. But if you need a ring to unlock then even if they give you the unlock button pressing it would do nothing.
As I’m new to the community I seem to only be able to post replies and not start a topic. But I found the message above really useful in installing my intercom with a Bitron MV100 video entryphone. As Artemu says it’s frustrating when what each wire does is not explained. My entryphone goes under other names including Series 70 which appears in the Ring app but that leads to a wholly incorrect wiring set up. Mine works (no video of course) by wiring A1 to terminal 1 and A2 A3 A5 and A6 to C. I haven’t yet checked sound quality and whether adding A4 to 1 improves that.
Further to my first post I found that adding A4 to terminal 1 did not improve sound quality and indeed seemed to make it slightly worse.
I seem to have got everything working except that intermittently if someone at the street door presses a button for a flat other that mine then my Ring app will sound but not the entry phone in my flat. I cannot get my head round how I might have achieved this but have decided to leave things alone and embrace this as an acceptable glitch for the time being.