Hi @Mroshan,

Please check that the SMS Service Center Number (SMSC) set in your smartphone is +49176000443.

Kind regards,
Alex

Its correct but still I couldn't send any sms :/

Hello @Mroshan,

welcome to our Community

Thank you @MXP_Alex for your support with this request.

What message do you get when you try to send an SMS?

Kind regards
Jessica

Could send message 

I received this sms after I reported my issue to o2 support:

Lieber o2 Kunde,

Wir haben Ihr Anliegen (Nr. S25265752) bearbeitet. Es liegt keine Netzstörung vor. 
Aus Sicherheitsgründen wurde Ihre SIM-Karte für den SMS-Versand gesperrt. Bitte wenden Sie sich direkt an die Kundenbetreuung.

Freundliche Grüße, Ihr o2 Team

After my second call they told me to wait 3 days…

Hello @Mroshan,

thank you for your information on your concern.
I have just checked again for you and can inform you that the order that the colleague took so that the block can be removed has already been finally processed.
In order for the change to actually become active, it is advisable to switch the mobile phone off and on again. After that, everything should work, so please let us know
Since I can see from the message that you are blocked from sending SMS messages for security reasons, I would like to recommend the third-party provider block. Have you already activated this?

All information about that you can find here: Third-party lock

Kind regards
Jessica