Which frequencies may not be used?

Amateur radio operators may only use the frequency bands allocated by the national regulatory authority and international agreements for the amateur radio service. It is prohibited to use frequencies intended for other services such as commercial broadcasting services, emergency radio services, military communications and aviation communications. The exact frequencies to avoid vary by country, and it is important to check with the local regulatory authority, such as the Federal Network Agency in Germany or the Federal Communications Commission (FCC) in the US, for an up-to-date list of what not to do frequencies to be used. In addition, the band plans of the amateur radio associations should also be taken into account, as these specify a detailed distribution of usage within the amateur radio bands.