Hi, I've connected my ERA100 successfully to my phone via Bluetooth and WI-FI. Now the reason I bought this product is because I want to use it when camping in a field with friends. As I have an Anker power pack and solar panel I want 24 hour music with better quality than a wireless speaker. My question:-  is it possible for a friend to connect their phone to the ERA100 via bluetooth without WI-FI or having the Sonos app installed on their phone ?