Make sure that any devices previously paired with the speakerphone are turned off.
If the status light is not steady in blue, first turn off the other device, then turn the speakerphone off and on. The status light becomes steady in blue and you hear “Ready to pair”.
If this doesn't resolve your issue, try resetting TX550. This will clear out all previously paired devices from the history.
To reset your TX500
Power down your device then power back on. Press the Call button while turning the Sonic Rider on and follow the voice prompts to reset your device.