I have the same intercom system with the three doorphones purchased from the Kavkas store. I later found out that it is a Greek company. Terrible! There are unacceptable makeshift holes in the box where the intercom should be screwed in. If you manage to get the Cypriot one to work, you are an expert. To put name tags on the doorbells, you have to be a specialist, it's unacceptable! When someone rings the bell, you press the button to talk and it keeps ringing! You wait a second or two and then you speak! Then you press the key to open the door, and if it doesn't open, you have to go down alone and open it! Great tool for exercising on the stairs. We changed all the wiring from the power supply to the Cypriot and managed to open the door from the first floor! We haven't achieved the desired result for the second and third floors yet! I would really like to know what the Greek side's contribution is to the final result of this unacceptable construction with the poor instructions! After a lot of trouble, I inform you that without the power supply, which you pay EXTRA for, the price is around 30 euros! The Cypriot is not going to work! Also, the system will never work properly due to: a) the poor buttons on the intercom that don't always work, b) the poor speaker-microphone, c) the software that provides unacceptable response times for the entire system. Stay away from this company, it's better to get a simple and cheap system, it will work better and if it breaks, which I don't think it will, you can just throw it away and get another one. Anyway, CTC does not provide any substantial support in the Greek province.