Message Stream
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Fast Pair requires an additional channel for a persistent connection with the
Providers to support Fast Pair extensions. When the Provider connects to a
supported Seeker, the Seeker will attempt to connect the message stream.
Supported Implementation
Fast Pair supports two kinds of message stream implementations:
RFCOMM
Use fixed UUID as the endpoint df21fe2c-2515-4fdb-8886-f12c4d67927c
L2CAP
Use GATT PSM Characteristic
to obtain the PSM value for L2CAP connection.
Once connected, messages can be exchanged in the following format:
The additional data length and additional data fields should be big endian.
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Last updated 2025-08-12 UTC.
[[["Easy to understand","easyToUnderstand","thumb-up"],["Solved my problem","solvedMyProblem","thumb-up"],["Other","otherUp","thumb-up"]],[["Missing the information I need","missingTheInformationINeed","thumb-down"],["Too complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-12 UTC."],[[["\u003cp\u003eFast Pair utilizes a persistent connection with Providers via an additional channel to enable Fast Pair extensions.\u003c/p\u003e\n"],["\u003cp\u003eTwo message stream implementations are supported: RFCOMM using a fixed UUID and L2CAP using GATT PSM Characteristic for connection.\u003c/p\u003e\n"],["\u003cp\u003eExchanged messages adhere to a specific format containing message group, message code, additional data length, and optional additional data.\u003c/p\u003e\n"],["\u003cp\u003eData length and additional data fields within messages are represented in big endian format.\u003c/p\u003e\n"]]],[],null,["# Message Stream\n\nFast Pair requires an additional channel for a persistent connection with the\nProviders to support Fast Pair extensions. When the Provider connects to a\nsupported Seeker, the Seeker will attempt to connect the message stream.\n\nSupported Implementation\n------------------------\n\nFast Pair supports two kinds of message stream implementations:\n\n### RFCOMM\n\nUse fixed UUID as the endpoint\n`df21fe2c-2515-4fdb-8886-f12c4d67927c`\n\n### L2CAP\n\nUse GATT [PSM Characteristic](/nearby/fast-pair/specifications/bledevice#message_stream_PSM \"message stream_PSM\") to obtain the PSM value for L2CAP connection.\n\nMessage Format\n--------------\n\nOnce connected, messages can be exchanged in the following format:\n\n| Octet | Data Type | Description | Mandatory? |\n|-------|-----------|------------------------|------------|\n| 0 | uint8 | Message group | Mandatory |\n| 1 | uint8 | Message code | Mandatory |\n| 2 - 3 | uint16 | Additional data length | Mandatory |\n| 4 - n | | Additional data | Optional |\n\nThe additional data length and additional data fields should be big endian."]]
