It sounds tempting: “This signal booster can boost your call quality and LTE data transmission.Enjoy fast data transfer and never miss a call or message again.” This is how Amazon advertises a cell phone repeater that costs just under 220 euros.The amplifier is said to support GSM and LTE frequencies in the 800 and 900 MHz range.The idea: A mobile phone signal from your mobile phone in the house should be picked up by an indoor antenna, processed by the amplifier and forwarded to a Yagi directional antenna on the house wall or roof via a 15 meter long cable that is included.The signal from the mobile phone transmission mast should come to your cell phone in the opposite way.The use is supposedly useful if you live in a house where the network coverage is weak.Outdoor reception is often good, but indoor reception is moderate.It is precisely these customers that Amazon is addressing with the offer from the manufacturer Orpey.Incidentally, the amplifier is also available with other frequency bands on board – and then significantly more expensive.But using such repeaters is not a good idea.This is because you are actively interfering with the cell phone network of the cell phone provider, which can lead to disruptions.Deutsche Telekom writes to us on request: “As a licensee of mobile communications frequencies, Deutsche Telekom (and all other network operators in Germany) is subject to the supervision of the Federal Network Agency.This means that we are responsible for any use of the frequencies assigned to us, including use in the case of repeaters.” It follows that the network operators must have access to the frequencies used at all times in case of doubt.This is necessary in order to be able to switch off the radio system at any time in the event of a fault.This also applies to repeaters.It goes on to say: “Due to these regulatory framework conditions, repeaters can or must be sold exclusively via the network operator.A right of access for the network operator (and thus a direct contractual relationship with the customer) must be given at all times.That is why there is no approval for manufacturers who sell their products independently (as in this case).”In plain language: If the mobile phone providers notice that you are using and using such a repeater, they will in all likelihood take action against it.It is unclear what the consequences will be for you.According to Telekom, these would be imposed by the regulator.However, if the worst came to the worst, Telekom would insist that the device be taken out of service and would also reserve the right to take legal action.Particularly nasty with the offer: According to the description text, the repeater comes “with CE and RoHS certificates”, which at least suggests that use in Germany is permitted.Incidentally, Telekom itself is experimenting with a repeater for end customers.The difference: Telekom brings the device onto the market that is tailored to its network and also knows where it is used.It is even attached by a Telekom technician - but unfortunately only in Bavaria at the moment.If you want to improve a bad signal to better connect your own mobile phone in your home to the outside world, we recommend using WiFi and the Wifi Calling feature (also called VoWifi).Your cell phone uses your internet line instead of the cell phone tower as the transport route for making calls with your cell phone contract.Your mobile operator must support this feature and you must activate it once in your mobile phone.Most modern cell phones support the function.We mark partner links with these symbols.If you click on such a link or button or make a purchase, we receive a small payment from the respective website operator.This has no effect on the price of a purchase.But you help us to continue offering inside digital free of charge.Thanks very much!Save my data in the browser to comment faster in the futureyour technique.to the point.Every week the latest news directly and clearly in the mailbox