Bluetooth HFP Support for Third-Party Device Phone Calls

#harmonyos #bluetooth #hfp #arkts

Read the original article：Bluetooth HFP Support for Third-Party Device Phone Calls

Context

Developers frequently ask whether HarmonyOS supports answering phone calls through third-party Bluetooth devices and what interface capabilities are available for this functionality.

Description

HarmonyOS provides comprehensive support for handling phone calls through Bluetooth-connected third-party devices using the Hands-Free Profile (HFP). The system includes dedicated APIs and protocols that enable seamless voice interaction between HarmonyOS devices and compatible Bluetooth accessories like headsets, car audio systems, and other hands-free devices.

The HFP protocol defines standardized processes for voice interaction between devices with two distinct roles:

AG (Audio Gateway): The audio source device responsible for audio transmission, contact information sending, and call control
HF (Hands-Free): The audio receiving/output device that handles user operations

Solution / Approach

1. Verify Device HFP Protocol Support

First, confirm that the target device supports the HFP protocol. Use the hfp.createHfpAgProfile method to create a HandsFreeAudioGatewayProfile instance and connect to the corresponding profile.

2. Implementation Steps

The Bluetooth development process follows these stages:

Device discovery
Device pairing and connection
Data connection and transmission

3. Code Implementation

import { connection, hfp, baseProfile, constant } from '@kit.ConnectivityKit';
import { BusinessError } from '@kit.BasicServicesKit';

export class PairDeviceManager {
  device: string = '';
  pairState: connection.BondState = connection.BondState.BOND_STATE_INVALID;
  hfpAg = hfp.createHfpAgProfile();

  // Define pairing state change callback function
  onBondStateEvent = (data: connection.BondStateParam) => {
    if (data && data.deviceId == this.device) {
      this.pairState = data.state; // Save target device pairing state
    }
  };

  // Initiate pairing, device address can be obtained through device discovery process
  public startPair(device: string) {
    this.device = device;
    try {
      // Subscribe to pairing state change events
      connection.on('bondStateChange', this.onBondStateEvent);
    } catch (err) {
      console.error('bondStateChange errCode: ' + (err as BusinessError).code + ', errMessage: ' + (err as BusinessError).message);
    }

    try {
      // Initiate pairing
      connection.pairDevice(device).then(() => {
        console.info('pairDevice');
      }, (error: BusinessError) => {
        console.error('pairDevice: errCode:' + error.code + ',errMessage' + error.message);
      });
    } catch (err) {
      console.error('startPair: errCode:' + err.code + ',errMessage' + err.message);
    }
  }

  // Define HFP connection state change callback function
  onHfpConnectStateChange = (data: baseProfile.StateChangeParam) => {
    // Handle HFP connection state changes
  };

  // Initiate connection
  public async connect(device: string) {
    try {
      let uuids = await connection.getRemoteProfileUuids(device);
      let allowedProfiles = 0;
      if (uuids.some(uuid => uuid == constant.ProfileUuids.PROFILE_UUID_HFP_HF.toLowerCase())) {
        console.info('device supports hfp');
        allowedProfiles++;
        this.hfpAg.on('connectionStateChange', this.onHfpConnectStateChange);
      }
      if (allowedProfiles > 0) { // If available profiles exist, initiate connection
        connection.connectAllowedProfiles(device).then(() => {
          console.info('connectAllowedProfiles');
        }, (error: BusinessError) => {
          console.error('errCode:' + error.code + ',errMessage' + error.message);
        });
      }
    } catch (err) {
      console.error('errCode:' + err.code + ',errMessage' + err.message);
    }
  }
}

let pairDeviceManager = new PairDeviceManager();
export default pairDeviceManager as PairDeviceManager;

Key Takeaways

HarmonyOS fully supports Bluetooth HFP protocol for third-party device phone call handling
The HFP module provides comprehensive APIs for Bluetooth call interface access
Device compatibility verification is essential before establishing HFP connections
Proper error handling and state management are crucial for reliable Bluetooth communication
The implementation requires following the standard Bluetooth development workflow: discovery, pairing, and connection