The idea of making the phone signal or anywhere else in the apartment both audibly and visually, is very welcome, especially for the elderly. Unfortunately, there is here on the Amazon page any product description, there is information on the side of Conrad (Order No .: 921401-62). It says: "Visual and acoustic signaling in rooms without telephone connection | radio range 30 m". I'd rather have ordered from Amazon, since I was here and it was an account incl. Shipping even a few cents cheaper. The product, however, is the same thing. The installation is surprisingly simple: Just plug the transmitter between TAE socket and telephone and three (not included) C batteries into the receiver. But the transmitter depends on the basis of very short cable directly into the socket. Since this is usually installed near the floor and in a corner, the transmitter is necessarily attached to a radio technically not optimal location. Now the somewhat chunky receiver should be at the neighboring hall, which corresponds to a distance of about 4m incl. A wooden door as an obstacle. Result: no signal. If one approaches the receiver to the transmitter to approximately 1-2 feet and eye contact, tone and red LED sign, but not reliably. Sometimes it does not work sometimes.
Conclusion: Thus, the practical experience is in no way compatible with the product description, because neither the promised wireless range of 30m (in open field) is piecemeal fashion, nor is it possible to wall / door bridging reliable, which is, however, suggests ("in rooms with no telephone connection "). The call signal transmitter went back, after all, the credit within two days was confirmed by return.