public String readSIMCard() {
            TelephonyManager tm = (TelephonyManager) this.getSystemService(TELEPHONY_SERVICE);//Get related system services
        StringBuffer sb = new StringBuffer();
                Switch(tm.getSimState()){ //getSimState() gets the state of sim. There are 6 states below.
                                Case TelephonyManager.SIM_STATE_ABSENT :sb.append("no card"); break; 
                                Case TelephonyManager.SIM_STATE_UNKNOWN :sb.append("unknown state"); break;
                                Case TelephonyManager.SIM_STATE_NETWORK_LOCKED :sb.append("Requires NetworkPIN Unlock"); break;
                                Case TelephonyManager.SIM_STATE_PIN_REQUIRED : sb.append("requires PIN unlock"); break;
                                Case TelephonyManager.SIM_STATE_PUK_REQUIRED : sb.append("requires PUK unlock"); break;
                                Case TelephonyManager.SIM_STATE_READY :sb.append("good");break;
        }

        if(tm.getSimSerialNumber()!=null){
                sb.append("@" + tm.getSimSerialNumber().toString());
        }else{
                                Sb.append("@Unable to get SIM card number");
        }

        if(tm.getSimOperator().equals("")){
                                Sb.append("@Unable to get vendor code");
        }else{
                sb.append("@" + tm.getSimOperator().toString());
        }

        if(tm.getSimOperatorName().equals("")){
                                Sb.append("@ ");
        }else{
                sb.append("@" + tm.getSimOperatorName().toString());
        }

        if(tm.getSimCountryIso().equals("")){
                                Sb.append("@Unable to acquire nationality");
        }else{
                sb.append("@" + tm.getSimCountryIso().toString());
        }

        if (tm.getNetworkOperator().equals("")) {
                                Sb.append("@Unable to get network operator");
        } else {
                sb.append("@" + tm.getNetworkOperator());
        }
        if (tm.getNetworkOperatorName().equals("")) {
                                Sb.append("@Unable to get network operator name");
        } else {
                sb.append("@" + tm.getNetworkOperatorName());
        }
        if (tm.getNetworkType() == 0) {
                                Sb.append("@Unable to get network type");
        } else {
                sb.append("@" + tm.getNetworkType());
        }
        return sb.toString();
    }