diff --git a/How-to-upgrade-4G-extension-firmware.md b/How-to-upgrade-4G-extension-firmware.md
index 03696c4..12aaef4 100644
--- a/How-to-upgrade-4G-extension-firmware.md
+++ b/How-to-upgrade-4G-extension-firmware.md
@@ -218,3 +218,18 @@ echo -en  "AT+CSQ\r\n" |sudo socat - /dev/ttyUSB2,crnl
 OK
 ```
 
+* get imei 
+```
+echo -en  "AT+CGSN\r\n" |sudo socat - /dev/ttyUSB2,crnl
+
+86263605126xxxx
+
+OK
+```
+```
+echo -en  "AT+CIMI\r\n" |sudo socat - /dev/ttyUSB2,crn
+46001341620xxxx
+
+OK
+```
+