Automatic 112 testing junction box for telephone

The utility model relates to an automatic 112 testing junction box for a telephone, which can use a zero passage detection control circuit to test zero passage signals at the time when 112 starts a test and to control the conduction of a G2 triode to make a relay attract and realize automatic changes of line terminal loads. When the test is completed, the utility model can cause a triode G1 to be conducted by a delaying control circuit and drive the relay to switch and return to the original state. The utility model has the advantages of quick and accurate test to data, convenient line detection and maintenance for telecommunication departments and convenient communication for users, which is regarded as a device worth being used widely.