It can connect to 2 devices. It's best to have the GPS on the second channel
4. Pair your GPS to the 20S using the Second Mobile Phone Pairing method. On the 20S, hold down the Jog Dial for 6 seconds until you hear the voice prompt say “intercom pairing” and you see the LED flash red rapidly then within 2 seconds press the phone button to hear the voice prompt say “second mobile phone pairing” and you see the LED flash blue rapidly.
5. While the 20S is in Second Mobile Phone Pairing mode, scan for the Sena 20S in the list of Bluetooth devices on your GPS and when it appears select it to pair the two devices together.