During receiving, you hear too much noise and hiss.

Analysis
1.The signal is poor. 
2.You may be in a position with poor signals, such as near a high building or in an underground area.
3.It may be the result of external disturbance (such as electromagnetic
interference).

Solution
1.Make sure call participants are within the communication range.
2.Move to an open and flat area, restart the radio, and try again.
3.Stay away from equipment that may cause interference.