维修电话机时,经常需要测试电话机在呼入时是否具有振铃的功能。一些专业报刊曾经介绍过几种方法,如向电话机送入低压交流电等等。其实,利用“300”或“201”电话业务,在不增加任何设备的情况下,可以轻而易举地进行测试。 测试方法是这样的,将需要测试的电话机接好线路以后,将“音频—脉冲”开关拨在“脉冲”一侧,然后摘机拨“300850”或“201”,等听到提示输入卡号时,拨0-9任意一个键,就 When repairing a telephone, it is often necessary to test whether the telephone has a ring function when incoming. Some professional newspapers have introduced several methods, such as sending low-voltage AC to the telephone and so on. In fact, the use of “300” or “201” telephone service, without any additional equipment, can easily be tested. The test method is this, the need to test the phone connected to the line, the “audio - pulse” switch on the “pulse” side, and then pick up “300850” or “201”, and so hear the prompt to enter the card number When dial 0-9 any one key, on