| 摘要 |
<p>The device for a telephone is used to prevent certain types of communications such as national or international calls. It can easily be integrated in a normal telephone network and does not require any special installation work. It consists of a small unit into which are fitted switching devices and is installed using two brackets. It does not load the lines and affect communication. When the caller calls a telephone code which must not be used, the device sends a false manoeuvre tone and releases the devices at the urban uniselector. The device is foolproof.</p> |
