APP活跃通话时接GSM电话，Telecom Connection的onHold/onUnhold未触发

我已在应用中集成Telecom子系统，并为Connection设置了CAPABILITY_SUPPORT_HOLD等能力。当应用处于活跃通话状态时，若收到GSM来电并接听，TelecomConnection类的onHold和onUnhold回调函数未被触发，反而onDisconnect回调被触发。请问我的实现是否存在遗漏？

相关代码 #

VoiceConnectionService 实现 #

class VoiceConnectionService : ConnectionService() {

   var activeConnection: Connection? = null

   override fun onCreateIncomingConnection(
        connectionManagerPhoneAccount: PhoneAccountHandle,
        request: ConnectionRequest
    ): Connection? {
        val incomingCallConnection = createConnection(request)
        incomingCallConnection?.setRinging()
        return incomingCallConnection
    }

    private fun createConnection(request: ConnectionRequest): Connection? {
        activeConnection = TelecomConnection()

        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
            (activeConnection as TelecomTwilioConnection).connectionProperties = Connection.PROPERTY_SELF_MANAGED
        }
        (activeConnection as TelecomTwilioConnection).connectionCapabilities = Connection.CAPABILITY_MUTE
        (activeConnection as TelecomTwilioConnection).connectionCapabilities = Connection.CAPABILITY_SUPPORT_HOLD
        return activeConnection
    }
}

TelecomConnection 实现 #

class TelecomConnection : Connection() {

   override fun onHold() { }
   override fun onUnhold() { }
}

Manifest 中 Service 配置 #

<service android:name=".twilio.telecom.VoiceConnectionService"
            android:label="VoiceConnectionService"
            android:permission="android.permission.BIND_TELECOM_CONNECTION_SERVICE"
            android:exported="false">
            <intent-filter>
                <action android:name="android.telecom.ConnectionService" />
            </intent-filter>
        </service>

你的实现存在几个关键问题，导致通话切换时触发onDisconnect而非预期的onHold/onUnhold：

1. 连接能力赋值错误
   connectionCapabilities是位掩码属性，需用|=操作符累加能力，直接赋值会覆盖之前的配置。你当前代码先设置CAPABILITY_MUTE，随后被CAPABILITY_SUPPORT_HOLD覆盖，最终仅HOLD能力生效，且类型转换存在错误——实例化的是TelecomConnection，却强制转为TelecomTwilioConnection，会直接抛出ClassCastException，导致连接创建失败。

正确写法：

// 修正能力赋值与类型问题
private fun createConnection(request: ConnectionRequest): Connection? {
    val connection = TelecomConnection()

    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
        connection.connectionProperties = Connection.PROPERTY_SELF_MANAGED
    }
    connection.connectionCapabilities = 
        Connection.CAPABILITY_MUTE or Connection.CAPABILITY_SUPPORT_HOLD
    activeConnection = connection
    return connection
}

2. 未注册PhoneAccount到Telecom系统
   Telecom需要识别你的应用通话账户，才能将其纳入系统通话管理流程。需在应用初始化时通过TelecomManager注册：

val telecomManager = getSystemService(Context.TELECOM_SERVICE) as TelecomManager
val packageName = packageName
val accountHandle = PhoneAccountHandle(ComponentName(packageName, VoiceConnectionService::class.java.name), "custom_account_id")
val phoneAccount = PhoneAccount.Builder(accountHandle, "应用通话账户")
    .setCapabilities(PhoneAccount.CAPABILITY_CALL_PROVIDER or PhoneAccount.CAPABILITY_SUPPORT_HOLD)
    .build()
telecomManager.registerPhoneAccount(phoneAccount)

3. 未正确同步通话状态到Telecom
   当系统触发保持/恢复操作时，你的Connection需要主动向Telecom确认状态变更：

class TelecomConnection : Connection() {

    override fun onHold() {
        // 执行你的通话SDK保持逻辑
        setOnHold() // 通知Telecom已进入保持状态
    }

    override fun onUnhold() {
        // 执行你的通话SDK恢复逻辑
        setActive() // 通知Telecom已恢复活跃状态
    }

    // 通话激活时调用此方法
    fun markAsActive() {
        setActive()
    }
}

4. 权限与配置检查
   确保已申请必要权限：

<uses-permission android:name="android.permission.READ_PHONE_STATE" />
<uses-permission android:name="android.permission.CALL_PHONE" />
<!-- Android 12及以下需添加 -->
<uses-permission android:name="android.permission.MODIFY_PHONE_STATE" />

若需跨应用交互，可将service的android:exported设为true，注意权限安全。

内容的提问来源于stack exchange，提问作者Jitendra Reddy