摘要 |
<p>The device for the exclusive use of a single telephone line by a telephone set in installations comprising a plurality of telephone sets (TF1...TFn) is connected between each telephone set and the line (a, b) and can connect to said line the first set whose handset is lifted and isolate all remaining sets from the line, while signalling at the same time on each isolated set the line seizure by another set, without requiring any modifications either in the telephone installation or in the individual sets.</p> |