Panasonic WX-ST400P Operating Instructions Manual page 26

Confirming pairing
4
Check the [REG] indicator on the receiver
While the microphone is in pairing confirmation mode, the [REG] indicator of the paired
channel on the wireless receiver will turn green and orange alternately. This allows to
confirm the pairing. The pairing confirmation mode lasts for five seconds, after which
the devices will go back to their normal operation mode. Press the [REG] button once
during pairing confirmation mode to go back to the normal operation mode.
If the [PWR] indicator on the microphone blinks red, the microphone is not
paired to a wireless receiver. Perform the steps described in "Pairing" (page
20).
The pairing confirmation can also be performed from the wireless receiver.
The microphone audio will be kept on transmitting during pairing
confirmation.
Also refer to the wireless receiver manual.
26
Register indicator