一.介紹

在應用層監聽通話狀態只有三種，從TelephonyManager.java中註釋可知這三種狀態含義如下：
    CALL_STATE_IDLE 空閒態(沒有通話活動)
    CALL_STATE_RINGING 包括響鈴、第三方來電等待
    CALL_STATE_OFFHOOK 包括dialing撥號中、active接通、hold掛起等
由上可知，active接通狀態沒有單獨給出，所以我們無法得知電話是否接通了，
因此需要其它手段來獲取更多的精確通話狀態，遍查網路資料，一般有兩種方法！

public class TelephonyManager {
    /** 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;
}

二.監聽9種通話狀態

法一.使用系統api監聽

條件: 
1.需要許可權android.permission.READ_PRECISE_PHONE_STATE、app打包時需要系統簽名、安裝在系統目錄等 
2.onPreciseCallStateChanged 精確通話回撥api在android.jar中被hide了, 可以使用反射或沒有被hide的android.jar解決

TelephonyManager telM = (TelephonyManager) getSystemService(TELEPHONY_SERVICE);
telM.listen(new
 
 PhoneStateListener(){
        /**
         * 當有精確通話狀態時回撥
         * Callback invoked when precise device call state changes
         * @hide 隱藏api,給系統app使用的
         */
        @Override
        public void onPreciseCallStateChanged(PreciseCallState callState) {
            //當有精確通話狀態時回撥
        }
    }, PhoneStateListener.LISTEN_PRECISE_CALL_STATE); //需要許可權android.permission.READ_PRECISE_PHONE_STATE

// 精確的九大通話狀態
public class PreciseCallState implements Parcelable {
    public static final int PRECISE_CALL_STATE_IDLE =           0; //通話空閒
    public static final int PRECISE_CALL_STATE_ACTIVE =         1; //正在通話(活動中)
    public static final int PRECISE_CALL_STATE_HOLDING =        2; //通話掛起(例如我和多個人通話,其中一個通話在活動,而其它通話就會進入掛起狀態)
    public static final int PRECISE_CALL_STATE_DIALING =        3; //撥號開始
    public static final int PRECISE_CALL_STATE_ALERTING =       4; //正在撥出(提醒對方接電話)
    public static final int PRECISE_CALL_STATE_INCOMING =       5; //對方來電
    public static final int PRECISE_CALL_STATE_WAITING =        6; //第三方來電等待(例如我正在和某人通話,而其他人打入時就會就進入等待狀態)
    public static final int PRECISE_CALL_STATE_DISCONNECTED =   7; //結束通話完成
    public static final int PRECISE_CALL_STATE_DISCONNECTING =  8; //正在結束通話
}

法二.讀取Logcat通訊日誌

條件: 
1.android 4.1以上需要root許可權，android 4.1以下版本只需新增日誌許可權android.permission.READ_LOGS
2.讀取通訊狀態：在root狀態下執行命令 logcat -v time -b radio

logcat日誌被劃分為以下幾個緩衝區
    -b <system, radio, events, main>
    main   — 主日誌緩衝區(預設,普通app應用)
    radio  — 無線/電話相關日誌緩衝區　　　
    events — 事件相關日誌緩衝區
    system — 系統相關日誌緩衝區

//正則表示式，匹配通話狀態
Pattern ptn = Pattern.compile("(\\d{2}\\-\\d{2}\\s\\d{2}\\:\\d{2}\\:\\d{2}\\.\\d{3}).*?GET_CURRENT_CALLS.*?,(\\w+),");
//Pattern ptn = Pattern.compile("(\\d{2}-\\d{2}\\s\\d{2}:\\d{2}:\\d{2}\\.\\d{3}).*?qcril_qmi_voice_all_call_status_ind_hdlr:.call.state.(\\d),");

//使用Root許可權，執行logcat命令
Process process = Runtime.getRuntime().exec("su");
PrintWriter pw = new PrintWriter(process.getOutputStream());
pw.println("logcat -v time -b radio"); //logcat命令, -v 詳細時間; -b radio 通訊相關日誌緩衝區
pw.flush();

//迴圈讀取通話日誌
BufferedReader br = new BufferedReader(new InputStreamReader(process.getInputStream()));
String strLine;
while ((strLine = br.readLine()) != null) {     
    Matcher matcher = ptn.matcher(strLine);
    if (matcher.find()) {// 匹配結果    
        String time = matcher.group(1);  //提取通話時間
        String state = matcher.group(2); //提取通話狀態
    }
}
pw.close();
br.close();
process.destroy();

三.圖解9種通話狀態