Reliable but it interferes in the reception itself

This alarm system is very reliable, responds well and false alarms are taken out through the simple but perfectly adequate operation of the sensors basically. So far so good. For this and especially considering the amount of clear 5 Stars.

But what did not work: When I'm working with the SIM card, the system interferes with itself and there is always a loud noise, what you may know, when you start a call with your phone and are near a speaker. I am aware that these 400 frequency is not the best on the market and would suffer here and there mal ne disorder, but within the system there should already be tuned so that the device does not interfere itself. Average twice a night there this noise. This is untenable. And when I call the alarm to be heard in the room, then there are also these nasty noise, so I do not really listen to what is in the room. So this feature is unnecessary given the self-interference. So far I have tried D2 and Eplus. Soon follows a D1-SIM card. I'll keep you up to date if it gets better.