1. If you have been connected to the device in the past make sure the filter is off:
2. Enable only one mobile near the device.
3. Make sure the device is on.
4. Make sure you enable Bluetooth on your mobile phone.
5. Make sure you enable GPS (location services) on your mobile phone (only relevant for android phones).
6. Place your mobile close to the device and see if it's communicating.
7. Verify the communication ability for other pHi-Tech devices.
8. Restart the Mobile and the pHi-Tech device.
9. For iPhone- Check the Bluetooth permission for the app is enabled
Settings-> Privacy->pHi-Tech is on
10. For android phones- go to Settings-> Battery & Power Saving-> Battery Usage-> Ignore Optimizations-> Turn on Bluetooth Options and Bluetooth MIDI service. Then restart your phone.