fe03 Status Beacon
Channel 27 uses fe 03 as its magic header and behaves as a status beacon or capability advertisement. Unlike the ff55 protocol on channel 14, channel 27 remains available across multiple connections with no session limitations.
Connection behavior
Section titled “Connection behavior”On RFCOMM connection, channel 27 immediately sends a 20-byte message:
fe 03 01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00Structure:
fe 03 - Magic header01 - Message type (possibly "status" or "capability")00 - 17 bytes of zeros (reserved or padding)The 17 trailing zero bytes may represent unused fields in a fixed-length status structure. This could indicate optional capabilities that are disabled or not configured on this particular device/firmware version.
Fixed response behavior
Section titled “Fixed response behavior”Channel 27 responds to any input with the same fixed 12-byte response:
10 00 09 08 33 9a 03 04 08 3c 10 01This response is identical regardless of what is sent — QC35-format commands, ff55-format commands, random bytes, or empty frames all produce the same 12-byte reply. The fixed-response behavior strongly suggests this is not a command channel but rather a capability advertisement or heartbeat mechanism.
The response bytes may encode device capabilities or configuration state, but without multiple devices or firmware versions to compare against, the individual field meanings remain unknown.
Amazon / Alexa connection
Section titled “Amazon / Alexa connection”The UUID 0xFE03 is a registered Bluetooth SIG member UUID assigned to Amazon. The NCH700 supports Alexa as a configurable voice assistant (along with Google Assistant and Siri), and this channel may be part of the Alexa integration pathway.
Possible roles for this channel:
- Alexa readiness indicator — the Bose Music app or an Alexa-enabled device could check this channel to determine if Alexa integration is active
- Capability negotiation — the 20-byte initial message and 12-byte response may describe supported Alexa features
- Wake word relay — though unlikely given the fixed-response behavior, the channel could become active when Alexa is configured as the voice assistant
Comparison to other channels
Section titled “Comparison to other channels”| Property | Channel 27 (fe03) | Channel 14 (ff55) | Channels 8/9 (QC35) |
|---|---|---|---|
| Session limited | No | Yes (first connection only) | No |
| Sends initial data | Yes (20 bytes) | Yes (6 bytes) | No |
| Responds to commands | Fixed response only | Selective (types 01, 04, 05) | Command-specific |
| Likely purpose | Status/capability beacon | NCH700 control protocol | Legacy command interface |