T.G.
I LOVE Philips Avent DECT monitors. I bought one with my first child (now 6) and then again when i had my second (now 2). there is no interference guaranteed. I have taken mine to my neighbors and sat there and once accidentally brought it 6 houses down and it still worked. It is pricier but for the price you've paid for 3 you can get 1. I also love it because you can set up the sensitivity. so you can hear every little thing in the room or set it to only go off when they cry. I tried 2 others for my 2nd baby before going back to Avent and it didn't come close. I don't think you can get it in the stores. I bought mine online. it also monitors the temperature in the room but i don't really use that feature.