Sony WH-XB900N Help Manual page 29

To disconnect, touch the headset again with the smartphone.
To connect a paired smartphone, perform step 3.
Unlock the screen of the smartphone if it is locked.
Hint
The above procedure is an example. For more details, refer to the operating instructions supplied with the Android smartphone.
If you cannot connect the headset, try the following.
Unlock the screen of the smartphone if it is locked, and move the smartphone slowly over the N-Mark.
If the smartphone is in a case, remove the case.
Check that the Bluetooth function of the smartphone is enabled.
If you touch the headset with an NFC-compatible smart phone, the smartphone terminates Bluetooth connection with any current
device, and connects to the headset (One-touch connection switching).
Related Topic
How to make a wireless connection to Bluetooth devices
Disconnecting the Android smartphone with one-touch (NFC)
Switching the device by one-touch (NFC)
Listening to music from a device via Bluetooth connection
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