Two or three telephones in the hotel room are down, and the telephones are ok. The telephone line has four cores, and two of them are kept, but the other two still can't get through.

Find the wiring table on the junction box and listen to whether it is normal. If it is normal, there is something wrong with the wiring from the junction box to the room. Check the wiring, re-press the crystal head of the secondary line to ensure that the terminals of the junction box are in good contact. If there is no wiring data, we have to short circuit on one side and measure with multimeter on the other to determine the wiring of the room and junction box.