If it's in Germany, then it might be due to different factors. Just to confirm, you are able to receive SMS message but unable to send message, right?
Please run the following AT command and send the command response with us to check:
at+qnvfr="/nv/item_files/modem/mmode/sms_domain_pref"
This is the response:
+QNVFR: 01
OK
Try the following AT command:
at+qnvfw="/nv/item_files/modem/mmode/sms_domain_pref",00
AT+QCFG="ims",2
Then reboot your router and see if SMS works
When entering the AT command the reply is „error“
I rebooted but still no SMS
Would you mind to bind your device to Goodcloud and share to support for remote troubleshooting?
After the Goodcloud sharing, please PM me the admin log info and the MAC address. Thanks