International roaming, forbidden networks, hidden sim toolkit on one plus 5T I have used international roaming many times before with my one plus 5T and my native Vodafone India providers roaming plan. But this time I landed in Germany and it did not work. 

I've been trying to debug and even on manual network selection most of the networks appear as "forbidden". Same networks used to latch on on earlier trips. My native Vodafone provider confirms that roaming is indeed active on my plan. 

I tried to reboot, reinsert the Sim but nothing works. 

One of the debug steps suggested involved steps in the Sim toolkit app. This app is somehow visible under apps but I cannot seem to find it anywhere. Ideas? How can I find where it is to use it. 

Even in network settings the sin toolkit option does not seem there. Other users seem to have it there. I cleared my cache but no help. 

Anything else I can try to fix this? 

I am on Android 8.1.0 and oxygen is version 5.1.7

Any tips are very welcome! I'm stuck here in Germany with no connectivity and my providers help desk is pretty useless. 

Eg. Would inserting the Sim into another device and then back into this one help? Are there roaming related settings that need to be pushed onto the Sim?
I had same problem with Airtel but in another country. But same SIM worked in same phone in some other countries. When I used to land in one particular country it won't latch to any network. I was having this problem for almost one year. I managed by inserting the SIM in a feature phone and it worked well. Finally I figured out what needs to be done to make it work in a smartphone. Please go to manual network selection and select your operator even if it shows as forbidden. It worked for me and might work for other also.