Customer has U1960,version is V200R003C00,U1960 connect to the carrier's device through the AT0 trunk, an outer-office user through the AT0 incoming call and the called phone does not have the CLIP
1、 Check whether the call display mode (FSK and DTMF), calling line identification presentation (CLIP) time (the first ringing tone before and after the first ringing tone). The AT0 incoming call display mode to FSK, calling line identification presentation (CLIP) time is after the first ringing tone,U1960 configurations. No exceptions are found.
2、 With data capture to voice information on the line, a discovery signal in strong noise interference exists. Noise interference severely affects the line valid information (FSK calling line identification presentation (CLIP) detection, as shown in the following figure.
3、check the grounding of equipment such as environment interference factors, bar to examine，found quipment grounding voltage is too large
quipment grounding voltage is too large，this will effect the calling number display，cause the Incoming call from AT0 trunk donot display the calling number
By adjustment equipment grounding environment, the incoming call has the number display, the problem has been resolved!Data capture again and obtains a proper line signals, noise interference is cleared, as shown in the following figure.
Ground check：（please do the step 1 test before all the steps）
1、equipment room grounding condition，use ground cables to connect the cabinet and equipment room walls on metal objects (for example, window, door, and the grounding bar) directly connect and then test whether improved.
2、test the voltage difference between the neutral wire of the socket on the rack and ground cables，set the multimeter to the DC voltage test range. If the voltage difference is close to 0V is qualified.
3、test the voltage difference between the ground point of U19 and the ground cable of the socket on the rack，If the voltage difference is close to 0V is qualified.
4、test the voltage difference between the a arbitrary point of the rack and the ground cable of the socket on the rack，If the voltage difference is close to 0V is qualified.
5、set the slot of the cabinet in the equipment room to all cascaded together, and ensure that the devices contained in the cabinet and the grounding connection of the cabinet together. Ensure that a minimum voltage of the device and the peer device are consistent with the voltage reference.
6、the power supply cables and analog signal cables do not tied together with wiring should be kept separate feeding.