Are GSM repeaters allowed in Germany?

GSM repeaters, also known as mobile phone amplifiers, are only permitted in Germany if they have approval from the Federal Network Agency or a corresponding CE marking that certifies conformity with European directives. The use of an unauthorized GSM repeater can cause interference with the mobile network and is therefore not permitted by law. Users must ensure that they only purchase and use approved devices. Unapproved devices can be confiscated by the Federal Network Agency and fines can be imposed on the operator.