There is always a risk of feedback with repeaters which can make them oscillate and completely wipe out a base station. That said, I am using two professional repeaters but they only cover a small part of each house. This is ín many cases a better solution: Put the cell phone at a place in the house where there is good coverage. If you have access to an Android phone, use the excellent app Netmonitor (author Parizene) to find the place with the best signal. Link the phone over Bluetooth to a XLINK BTTN station http://www.myxlink.com/xlink_bttn.aspx Connect the BTTN device with a short or long cable to a Dect telefon base of which there are many (siemens, Panasonic etc). Three different cell phones can be linked to the BTTN device and you can use as many dect handsets as you want. You can also use standard (not cell) telephones connected with cable to the BTTN device, for example if there is telephone cabling in the house. So old people don't need to learn to handle cell phones. With adapters, you can even use antique rotatory phones http://telephones.newenglandhistorywalks.com/background. This is an improved xlink bttn manual since the original is awful. https://f3ee4b06-a-43c8cdc8-s-sites....attredirects=0 I am using the xlink system in an office on the ground floor in town where there is only coverage at the windows. The Panasonic DECT phone has an extremely strong signal and can be used throughout the whole apartment, deep inside the buidling. If not, another base station could be used and connected to the BTTN with cable. Of course, there is a problem if you can't find a good cell signal without using an external antenna. The ultimate solution is to connect an external antenna directly to your cell phone (which should be within bluetooth reach of the BTTN, less than about ten meters). This can be done to the antenna test connector in many Samsung phones, easier with older models where the test connector is bigger and less fragile. I like the GT-S7580 for this purpose. You can buy the patch cables needed for the connection from Australia where the XLINK BTTN solution is popular since it is very much forbidden to use repeaters. Fines are very high. http://onwireless.com.au/mobile-phon...ch-cables.html I have also used patch leads to connect two external antennas to the Samsung S4 for LTE. With the S5 and later, the test connectors are much smaller so here you need to rely on indirect coupling over cradles etc. One solution which I use with iphones is the "passive radiator pad" which in effect is an 8 dBi flat antenna large enough to place three phones on. http://onwireless.com.au/8dbi-all-ba...repeaters.html You then connect the antenna pad to a well positioned and efficient GSM or 3G antenna. The coupling loss with the pad is about 6 dB according to my testing (Large flat panel 900 MHz external antenna directly connected to phone test connector versus phone on antenna pad. Only using the phones own antenna gave 10 dBm weaker signal than the pad plus external antenna. To be expected since smart phone antennas have -4 to -6dBi loss in relation to an isotropic antenna). For the Wittenberg Antennen-Koppler I haven't found any documentation. With this solution, you'll have excellent coverage even in a large house (around my 340 sqm brick villa, the Dect phone reached 30 meters outside of the house when I tested calling over the XLINK connected cell phone ). Cell coverage in the house is spotty, so I need to use either a repeater (which has limited coverage) or the XLINK Bluetooth repeater. With Bluetooth active on the phone, it will connect automatically to the XLINK as it gets within ten meters range. There have been reports that the Bluetooth link will not be reestablished if there is a power outage on the Xlink - for some phones. Testing needed. For critical purposes, you might want to add a 9 volt backup. If the pairing is broken, the phone should be brought out of range from the XLINK and then back for the link to be reestablished. If you study the onwireless site, there is more on the subject. The bottom line is that while many people look for repeaters, they would often be better served with Bluetooth relays such as the XLINK BTTN and you don't break any laws and don't need to worry about disturbing the cell phone system. The XLINK Bttn is expensive if ordered in the EU or from Canada. If you buy some other equipment from onwireless in Australia, the XLINK Bttn price is good and delivery costs shouldn't bee too bad. By the way, there ought to be a German importer of the XLINK devices that we could order from...) (I recommend the android netmonitor app mentioned. If used with a phone which has a Mediatek chip, the app will show all base stations that can be heard and their signal strengths. This also works with dual sim card phones such as Alcatel One touch. The app shows the results from both cards including all neighbor cells. Other good apps to try are RF Signal Tracker and GSM signal monitoring (it can't be downloaded for samsung, which is a pity since it is the only app which simultaneously makes a chart over the signal strengths from all neighbor cells). Wenn sie Fragen hätten werde ich es versuchen auf Deutsch zu antworten.