Hello @Mesr 

Does it help to manually choose another provider/operator or just a restart of your phone?

Have you checked your T-Mobile account under blokkades to see if you have a barring active for use outside NL?

Also have you paid all invoices? An open invoice can result in a barring for use outside NL.

If your subscription is not older then 2 months yet than you will have a barring for use outside NL, this barring automatically gets removed after 2 months 

hi I try to register to all network it gives me message your sim card doesn't allow a connection to this network, i checked my T-Mobile account under blokkades nothing blocked, I just had an old bill and I'm paying it in installments, and my contract from more than one year