Bluetooth Classic Accessory Interface Specification

Overview

The Bluetooth Classic Accessory Interface Specification defines how a mobile device (such as Android phone) communicates with a BlueParrott headset using Bluetooth Classic through an AT‑command–based interface. At the core of the interface is a structured set of AT commands exchanged over the Classic Bluetooth link. This design uses standardized and vendor‑specific AT command prefixes to organize functional areas, with each command representing a specific feature or data channel. AT commands define what the headset exposes such as button events, mode changes, logs, sensor values, or model information, and specify whether the application can query, configure, or receive event notifications through the Bluetooth Classic connection.

Read Commands

Command	Description	Command Definition	Response Definition
INIT	Sent to headset to request Init Response	AT+ANDROID: BP, INIT	AT+ANDROID=BP, MODE, `mode` AT+ANDROID=BP, BONDABLE, `bondable` AT+ANDROID=BP, SPEEDDIAL, `speed dial #` AT+ANDROID=BP, APPNAME, `app name` AT+ANDROID=BP, APPKEY, `app key` AT+ANDROID=BP, MODEL, `model` AT+ANDROID=BP, PBVERSION, `pb version` AT+ANDROID=BP, FWVERSION, `fw version` AT+ANDROID=BP, CMFBVERSION, `cmfb version` AT+ANDROID=BP, S1STATE, `sensor state` AT+ANDROID=BP, S2STATE, `sensor state` AT+ANDROID=BP, S3STATE, `sensor state` AT+ANDROID=BP, VERBOSITY, `verbosity` AT+ANDROID=BP, TXNR, `tx noise reduction mode` AT+ANDROID=BP, TXGAIN, `tx gain mode` AT+ANDROID=BP, TEMPERATURE, `temperature value in °C` AT+ANDROID=BP, ENDINIT AT+ANDROID=BP, ENTKEY1, `Enterprise Key 1` AT+ANDROID=BP, ENTKEY2, `Enterprise Key 2` AT+ANDROID=BP, ENTKEY3, `Enterprise Key 3` AT+ANDROID=BP, ENDENTINIT
STATE	Sent to headset to request State Response	AT+ANDROID: BP, STATE	AT+ANDROID=BP, MODE, `mode` AT+ANDROID=BP, BONDABLE, `bondable` AT+ANDROID=BP, SPEEDDIAL, `speed dial #` AT+ANDROID=BP, APPNAME, `app name` AT+ANDROID=BP, APPKEY, `app key` AT+ANDROID=BP, MODEL, `model` AT+ANDROID=BP, PBVERSION, `pb version` AT+ANDROID=BP, FWVERSION, `fw version` AT+ANDROID=BP, CMFBVERSION, `cmfb version` AT+ANDROID=BP, S1STATE, `sensor state` AT+ANDROID=BP, S2STATE, `sensor state` AT+ANDROID=BP, S3STATE, `sensor state` AT+ANDROID=BP, VERBOSITY, `verbosity` AT+ANDROID=BP, TXNR, `tx noise reduction mode` AT+ANDROID=BP, TXGAIN, `tx gain mode` AT+ANDROID=BP, TEMPERATURE, `temperature value in °C` AT+ANDROID=BP, ENDSTATE AT+ANDROID=BP, ENTKEY1, `Enterprise Key 1` AT+ANDROID=BP, ENTKEY2, `Enterprise Key 2` AT+ANDROID=BP, ENTKEY3, `Enterprise Key 3` AT+ANDROID=BP, ENDENTSTATE

Write Commands

Command	Description	Values	Command Definition
MODE	Sent to headset to write the button Mode key, see VXI_BUTTON_MODE, `mode` is the string representation of a decimal number	0: Mute 2: SDK Mode 7: Voice Control 12: Check Battery 41: Second MFB 46: Answer/End Calls	AT+ANDROID: BP, MODE, `mode`
BONDABLE	Sent to headset to write the Bondable key, see VXI_BONDABLE, `bondable` is the string representation of a decimal number	0: not bondable 1: bondable	AT+ANDROID: BP, BONDABLE, `bondable`
SPEEDDIAL	`deprecated`	`deprecated`	`deprecated`
APPNAME	Sent to headset to write the App Name key, see VXI_APPNAME, `app name` is the application name as a string, maximum of 22 characters. Note that strings must be packed into / unpacked from the memory location. Chip memory is 16 bits wide, so 2 chars / WORD		AT+ANDROID: BP, APPNAME, `app name`
APPKEY	Sent to headset to write the App ID key, see VXI_APPID, is a string representing the application type (kdk, esc), maximum of 22 characters. Note that strings must be packed into / unpacked from the memory location. Chip memory is 16 bits wide, so 2 chars / WORD		AT+ANDROID: BP, APPKEY, `app key`
ENTKEY1	Sent to headset to write Enterprise Key 1, see BP_ENT_1, `Enterprise Key 1` is a 16 bit decimal value		AT+ANDROID: BP, ENTKEY1, `Enterprise Key 1`
ENTKEY2	Sent to headset to write Enterprise Key 2, see BP_ENT_2, `Enterprise Key 2` is a 16 bit decimal value		AT+ANDROID: BP, ENTKEY2, `Enterprise Key 2`
ENTKEY3	Sent to headset to write Enterprise Key 3, see BP_ENT_3, `Enterprise Key 3` is a 16 bit decimal value		AT+ANDROID: BP, ENTKEY3, `Enterprise Key 3`
VERBOSITY	Sent to headset to set the verbosity level		AT+ANDROID:BP, VERBOSITY, `level`
BLE_ADVERTISE_ON	Sent to headset to enable/disable BLE advertisement		AT+ANDROID: BP, BLE_ADVERTISE_ON, `boolean`
CLASSIC_PTT_ON	Sent to headset to enable/disable Classic PTT		AT+ANDROID: BP, CLASSIC_PTT_ON, `boolean`
PTTOC_ON	Sent to headset to enable/disable Push-to-Talk over Cellular		AT+ANDROID: BP, PPTOC_ON, `boolean`
SHARED_DEVICE_MODE	Sent to the headset to enable/disable shared device mode		AT+ANDROID: BP, SHARED_DEVICE_MODE, `boolean`
QR_CODE_SCAN_MODE	Sent to the headset to enable/disable QR Code mode		AT+ANDROID: BP, QR_CODE_SCAN_MODE, `boolean`
TX_DSP_MODE	Set microphone noise suppression mode	0: High 1: Medium (Default) 2: Off	AT+ANDROID=BP,TXNR, `mode`
TX_GAIN_MODE	Set microphone gain mode	0: -5dB 1: -4dB 2: -3dB 3: -2dB 4: -1dB 5: 0dB 6: 1dB 7: 2dB 8: 3dB 9: 4dB 10: 5dB 255: AGC (Auto Gain Control)	AT+ANDROID=BP,TXGAIN, `mode`

Notify Commands

Command	Description	Values	Payload
TEMPERATURE	Send notification to client when the temperature changes its value +/-1 deg C°		AT+ANDROID=BP, TEMPERATURE, `temperature value in °C`

Message Complete

Command	Description	Response Definition
ENDINIT	Sent from headset to indicate end of Init Response	AT+ANDROID=BP, ENDINIT
ENDSTATE	Sent from headset to indicate end of State Response	AT+ANDROID=BP, ENDSTATE
ENDENTINIT	Sent from headset to indicate end of Enterprise Init Response	AT+ANDROID=BP, ENDENTINIT
ENDENTSTATE	Sent from headset to indicate end of Enterprise State Response	AT+ANDROID=BP, ENDENTSTATE

Button Events

Command	Description	Response Definition
PTT,P	When the Parrott button is pressed	AT+ANDROID=BP, PTT,P
PTT,R	When the Parrott button is released	AT+ANDROID=BP, PTT,R
PTT,T	When the Parrott button is single tapped	AT+ANDROID=BP, PTT,T
PTT,D	When the Parrott button is double tapped	AT+ANDROID=BP, PTT,D
PTT,L	When the Parrott button is long pressed	AT+ANDROID=BP, PTT,L
PTT,P	When the Parrott button is pressed	AT+ANDROID=BP, PTT,P

Log Events

Command	Description	Response Definition
BP_LOG	Logging message from the headset	AT+ANDROID=BP,BP_LOG,`key`:`value`

Monitor and Parse AT Commands from Headset [Code Sample]

The following example monitors Broadcast Receiver class Intents sent when the OS receive an AT Command over SPP. Prior to subscribing to the intent, use the filter to select the category(ies) and Action(s) that are needed – in the below example the usage it to monitor Jabra/Blueparrott events which uses Google’s Assigned number (+ANDROID) and Plantronics' Assigned number to monitor KODIAK events. It also listens to actions such as HEADSET_EVENT along with ACL_DISCONNECTED. The section pertaining to the parsing of the command and the action corresponding to each can be customized to fit the supported use cases and needs.


@SuppressLint("MissingPermission")
private void registerClassicReceivers() {
    IntentFilter btIntentFilter = new IntentFilter();
    Log.e(TAG, "registerClassicReceivers");
    /*
    Jabra / BlueParrott AT events uses +ANDROID (GOOGLE) suffix
    EXAMPLE: AT+ANDROID BP, PTT, P
    */
    btIntentFilter.addCategory(BluetoothHeadset.VENDOR_SPECIFIC_HEADSET_EVENT_COMPANY_ID_CATEGORY + "." + BluetoothAssignedNumbers.GOOGLE);
    /*
    OPTIONAL: The usage of PLANTRONICS is to monitor Kodiak AT commands
    */
    btIntentFilter.addCategory(BluetoothHeadset.VENDOR_SPECIFIC_HEADSET_EVENT_COMPANY_ID_CATEGORY + "." + BluetoothAssignedNumbers.PLANTRONICS);
    btIntentFilter.addAction(BluetoothHeadset.ACTION_VENDOR_SPECIFIC_HEADSET_EVENT);
    btIntentFilter.addAction(BluetoothDevice.ACTION_ACL_DISCONNECTED);
    m_context.registerReceiver(new BroadcastReceiver() {
        @Override
        public void onReceive(Context context, Intent intent) {
            String action = intent.getAction();
            if (BluetoothHeadset.ACTION_VENDOR_SPECIFIC_HEADSET_EVENT.equals(action)) {
                Bundle eventExtras = intent.getExtras();
                if(eventExtras == null) {
                    return;
                }
                //get the arguments that the headset sent
                Object[] args = (Object[]) eventExtras.get(BluetoothHeadset.EXTRA_VENDOR_SPECIFIC_HEADSET_EVENT_ARGS);
                if (args == null) {
                    Log.e(TAG, "Null args for vendor specific event");
                    return;
                }
                String qualifier = (args.length >= 1) ? "" + args[0] : "";
                String eventName = (args.length >= 2) ? "" + args[1] : "";
                String data = (args.length >= 3) ? "" + args[2] : "";
                if (args.length == 3) {
                    Log.e(TAG, "[R]: " + qualifier + "," + eventName + "," + data);
                } else {
                    Log.e(TAG, "[R]: " + qualifier + "," + eventName);
                }
                data = data.toLowerCase();
                if (eventName.equals("PTT")) {
                    //PB EVENTS
                    if (data.equals("p")) {
                        handleButtonEvent(PB_BUTTON_DOWN);
                    } else if (data.equals("r")) {
                        handleButtonEvent(PB_BUTTON_UP);
                    } else if (data.equals("d")) {
                        handleButtonEvent(PB_BUTTON_DOUBLE_TAP);
                    } else if (data.equals("l")) {
                        handleButtonEvent(PB_BUTTON_LONG_PRESS);
                    } else if (data.equals("t")) {
                        handleButtonEvent(PB_BUTTON_TAP);
                    }
                }
            } else if (BluetoothDevice.ACTION_ACL_DISCONNECTED.equals(action)) {
                Log.e(TAG, "Headset got disconnected");
            }
        }
    }, btIntentFilter);
}

Send AT Commands to Headset [Code Sample]

private BluetoothHeadset mBluetoothHeadset = null; //init onServiceConnected
private BluetoothDevice mHfpDevice = null; // init based on adapter.getBondedDevices()
String command = "+ANDROID";
String args = agrs0 + "," + args1 + ", " + args2; //Example BP,MODE,2
When all combined:
AT+ANDROID:BP,MODE,2 → This will set the PB to a mode to send PTT events


@SuppressLint("MissingPermission")
private boolean sendVendorAT(BluetoothDevice device, String command, String args) {
    Log.d(TAG, "AT" + command + ":" + args);
    if (mHfpDevice == null ){
        Log.d(TAG, "mHfpDevice object is null");
        return false;
    }
    if (mBluetoothHeadset == null ){
        Log.d(TAG, "mBluetoothHeadset object is null");
        return false;
    }
    logStatus("AT" + command + ":" + args);
    return mBluetoothHeadset.sendVendorSpecificResultCode(device, command, args);
}