Prior to the liberalisation of the telecommunications market, certain telecommunications terminal equipment and telecommunications transmission equipment could be placed on the market and used only after having been appropriately authorised. This applied to telephones as well as modems, data transmission equipment
or other components. Since liberalisation, many approval restrictions forterminal equipment
and transmission equipment have been lifted. In general, an approval can be regarded as a sovereign act which is carried out after successful technical testing by the respective national authority. In the Federal Republic of Germany, such approvals are granted by the Federal Office for Approvals in Telecommunications (BZT) in Saarbrücken.