In Germany, signal boosters must be approved by the Federal Network Agency (Bundesnetzagentur)[1]. Devices need to have Bundesnetzagentur approval, and it is essential to follow their guidelines to prevent network interference[1]. Using uncertified devices can lead to fines and confiscation[1]. Signal boosters used in Germany should also be CE-certified[3][6][7].
Citations:
[1] https://www.mobilesignalguru.com/blog/legal-requirements-and-regulations-for-mobile-signal-boosters/
[2] https://apps.fcc.gov/kdb/GetAttachment.html?id=Ow2JaTt7gTZSK1xuGG2b7g%3D%3D&desc=935210+D02+Signal+Booster+Certification+v04r03&tracking_number=20673
[3] https://mysignalboosters.com/de/faqs/
[4] https://ec.europa.eu/docsroom/documents/7718/attachments/1/translations/en/renditions/native
[5] https://eu.hiboost.com/certificates/
[6] https://mysignalboosters.com/blog/4g-mobile-signal-booster-everything-you-need-to-know-about/
[7] https://mysignalboosters.com/de/provider/telekom-mobile-signal-booster/
[8] https://www.myamplifiers.com/articles/find-the-best-signal-booster-for-your-mobile-phone/