获取操作之间的事件用户按呼叫按钮和当用户开始听到呼叫声音

我在电话管理器中发现3个事件,但如何测量电话连接订户所需的时间?有可能吗?

/** Device call state: No activity. */
    public static final int CALL_STATE_IDLE = 0;
    /** Device call state: Ringing. A new call arrived and is
     *  ringing or waiting. In the latter case, another call is
     *  already active. */
    public static final int CALL_STATE_RINGING = 1;
    /** Device call state: Off-hook. At least one call exists
      * that is dialing, active, or on hold, and no calls are ringing
      * or waiting. */
    public static final int CALL_STATE_OFFHOOK = 2;