diff --git a/nmcli-with-gsm.md b/nmcli-with-gsm.md
index 5f88171..ee6518e 100644
--- a/nmcli-with-gsm.md
+++ b/nmcli-with-gsm.md
@@ -204,6 +204,16 @@ sudo gpio write 15 0
 # Enable ModemManager debug  
 change `/etc/systemd/system/dbus-org.freedesktop.ModemManager1.service`  
 add --debug after `/usr/sbin/ModemManager`  
+```bash
+...
+[Service]
+Type=dbus
+BusName=org.freedesktop.ModemManager1
+ExecStart=/usr/sbin/ModemManager --debug
+StandardError=null
+Restart=on-abort
+...
+```
 Then  
 
 ```