| 摘要 |
The invention relates to a plug device (10) which may be locked to a conventional shuttered telephone socket, and which device includes an outlet socket (50) into which a telephone may be plugged, and electronic means between the plug (14) and socket (50) to perform a call barring function. The plug device comprises a housing and a plug (14), the plug in use engaging behind a socket shutter (27) locked in place by a member (25). The outlet socket (15) is normally closed by a shutter (57) and telephone entry blocked by a member (50) held inplace by a catch (54). On rotation, projections on a key (16) displace catch (54) to allow telephone entry, and release hooked arms on a slide (20) from housing projections. The key is then moved inwardly to move slide (20) to cam (32) a shoulder on member (25), which is thus withdrawn to free the shutter (27). A slide portion (37) also pivots a lever (38) to lift the shutter (27) free of the plug (14). A screen (29) and pads (30, 31) prevent access to an installed plug (14). A pcb (60) supports call barring electronics comprising a relay, a line detection device and microprocessor. Unbarred calls pass unhindered but barred calls pass only on supply of an authorised identification number. Call time limits may be applied, expiry being indicated by tones or a display, and keypad programming is provided. <IMAGE>
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