diff --git a/How-to-use-the-4G-extension.md b/How-to-use-the-4G-extension.md
index 5c8774e..faf5449 100644
--- a/How-to-use-the-4G-extension.md
+++ b/How-to-use-the-4G-extension.md
@@ -8,7 +8,25 @@ run `enable_4g_cm4.sh` or `uconsole-4g-cm4 enable`, depends on the version of yo
 
 Please wait for it to complete, which may take about 20 seconds. Please be patient and try not press ctrl+c.  
 
-then use `mmcli -L` to see if there is a modem like 
+next is important, to check the version of your 4G extension by AT commands:
+
+```
+echo -en "AT+CUSBPIDSWITCH?\r\n" | sudo socat - /dev/ttyUSB2,crnl
+```
+
+we expecting to see **9001**
+
+if you are other module number ,eg :9011
+
+you don't need any following steps
+
+just make suer the sim card inserted  correctlly,and use **sudo ifconfig** to see if there is a **usb0** 
+
+if there is a usb0,then all is set, now you can use 4G card to view internet
+
+## 9001 part
+
+use `mmcli -L` to see if there is a modem like 
 
 ```
 /org/freedesktop/ModemManager1/Modem/0 [QUALCOMM INCORPORATED] SIMCOM_SIM7600G-H