求助：Connection类里面的onCreateOutgoingConnection方法的重写问题

对于android的拨号流程，网上有很多帖子分析，基本上都会有如下的描述：
“如果是MO，会调用ConnectionService端的onCreateOutgoingConnection(),这个方法会被TelephonyConnectionService重写，最终在TelephonyConnection里面执行，TelephonyConnectionService是最终要实例化的类”
问题是，我真没有发现TelephonyConnection是在哪里被实例化的，没有实例化的话，为什么ConnectionService里面的onCreateOutgoingConnection会在TelephonyConnection里面执行

TelephonyConnection具体实现分为GSM跟CDMA两个
packages/services/Telephony/src/com/android/services/telephony/GsmConnection.java
packages/services/Telephony/src/com/android/services/telephony/CdmaConnection.java

    private TelephonyConnection createConnectionFor(
            Phone phone,
            com.android.internal.telephony.Connection originalConnection,
            boolean isOutgoing) {
        TelephonyConnection returnConnection = null;
        int phoneType = phone.getPhoneType();
        if (phoneType == TelephonyManager.PHONE_TYPE_GSM) {
            returnConnection = new GsmConnection(originalConnection);
        } else if (phoneType == TelephonyManager.PHONE_TYPE_CDMA) {
            boolean allowMute = allowMute(phone);
            returnConnection = new CdmaConnection(
                    originalConnection, mEmergencyTonePlayer, allowMute, isOutgoing);
        }
        if (returnConnection != null) {
            // Listen to Telephony specific callbacks from the connection
            returnConnection.addTelephonyConnectionListener(mTelephonyConnectionListener);
        }
        return returnConnection;
    }