Check the validity of the SIM card for Android

CellSignalStrength.java

public abstract class CellSignalStrength {

    public static final int SIGNAL_STRENGTH_NONE_OR_UNKNOWN = 0;

    public static final int SIGNAL_STRENGTH_POOR = 1;

    public static final int SIGNAL_STRENGTH_MODERATE = 2;

    public static final int SIGNAL_STRENGTH_GOOD = 3;

    public static final int SIGNAL_STRENGTH_GREAT = 4;
    ... ...
}
//If the signal strength of SIM card is efficacious, the level must greater than 0.

isSimNetworkReady.java

@TargetApi(Build.VERSION_CODES.LOLLIPOP)
private static boolean isNetworkReady(Context context) {
    TelephonyManager manager = (TelephonyManager) context.getSystemService(Context.TELEPHONY_SERVICE);
    if (manager != null) {
        // Need Manifest.permission.ACCESS_COARSE_LOCATION add do check by your own
        @SuppressLint("MissingPermission") List<CellInfo> infoList = manager.getAllCellInfo();
        for (CellInfo info : infoList) {
            if (info.isRegistered()) {
                if (info instanceof CellInfoGsm) {
                    CellSignalStrengthGsm gsm = ((CellInfoGsm) info).getCellSignalStrength();
                    if (gsm.getLevel() > 0) {
                        return true;
                    }
                } else if (info instanceof CellInfoCdma) {
                    CellSignalStrengthCdma cdma = ((CellInfoCdma) info).getCellSignalStrength();
                    if (cdma.getLevel() > 0) {
                        return true;
                    }
                } else if (info instanceof CellInfoWcdma) {
                    CellSignalStrengthWcdma wcdma = ((CellInfoWcdma) info).getCellSignalStrength();
                    if (wcdma.getLevel() > 0) {
                        return true;
                    }
                } else if (info instanceof CellInfoLte) {
                    CellSignalStrengthLte lte = ((CellInfoLte) info).getCellSignalStrength();
                    if (lte.getLevel() > 0) {
                        return true;
                    }
                }
            }
        }
    }
    return false;
}

检查SIM卡有效性，需要 权限。原理即检测SIM卡信号，如果信号大于0即表示SIM卡有效。