To pair your SRS XB21 Sony BT speaker with a Bluetooth device for the first time, or to refresh old linkage info in that device, you have to know how to start up discovery mode on this Bluetooth speaker. Now in this mode, the speaker sends out its name and currently valid connection information over the Bluetooth airwaves, so that nearby devices can find and join with it. Thus in this post, we show you how to make the Sony SRS XB21 wireless speaker discoverable, to let you sync it with phones, tablets, computers, and smart speakers.
How to Make Sony SRS XB21 Discoverable, Step by Step Help
1. Turn On the XB21
Firstly, turn on the speaker by rapidly pressing its Power button.
E.g. See this button, pointed out by the cyan arrow, in the next picture.

The speaker then boots.

2. Press and Hold the Power-Pairing Button for One or Two Seconds
Secondly, to place the speaker into discovery mode, you press and hold the double-duty Power-Pairing button. E.g. See the location of this button in the picture above.
Release the button when the status lamp begins fast blinking and the speaker makes a rising set of beeps and announces “Bluetooth pairing…” in a female voice. The unit is now discoverable by other devices.
Note also that putting the speaker in discovery mode does not erase its prior memorized Bluetooth connections. It just allows you to connect to and add new devices to its memory.
Now if the speaker is in a corrupt state and will not go into discovery mode, you can reset it and see if that solves the problem. We describe that process in our How to Reset Sony SRS XB21 Wireless Speaker post.
3. Done with How to Make Sony SRS XB21 Discoverable

Finally, while the Bluetooth Status lamp is fast blinking, you should see the XB21 on any in-range phone, computer, tablet, or smart speaker, that is within several feet of it, as we see in the last picture. The speaker appears as “SRS-XB21” there.
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References for How to Make Sony SRS XB21 Discoverable
Revision History
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- 2021-09-24: First published.