Step 1. Get one of HM100P into pairing mode.
Form power off, press and hold MFB button for 3 to 5 seconds until the LED flashes blue and red alternately.
Step 2. Setting the other HM100P.
Press and hold the MFB button until Blue LED is steady.
Step 3. Pair and connect them.
Please keep both of them within 1 meter. And wait for about 30s.
Until the LEDs of both HM100P will flash BLUE twice every 4s.
Now you use them intercom function.