wireless voice door phone for long distance 500m 1V3 1,2.4G ISM Public Frequency Band: ... 2479MHz 2,Transfer rate:250K wireless voice door phone for long distance 500m 1V31,2.4G ISM Public Frequency Band:2402MHz-2479MHz2 ... seconds3,CALLA:First press the ID number, then the CALL button, enter the main CALL with the red lightB:No ... , re-timed one minute. wireless voice door phone for long distance 500m 1V3