offhook การใช้

• This ( telco : " manual branch exchange " or " MBE "-the manual precusor of the automatic MDF ) features a little lamp which is lit when a customer's pair is offhook, a lamp that's extinguished when a relay in the MBE sees the CPE's hookswitch close.
• So to make a call a customer would go offhook; this makes the corresponding lamp light; the operator plugs her headset into a special socket beside the lamp; the customer tells the operator the number he wants; the operator makes the call ( a more envolved procedure which we needn't go into ).