Pixel 5 sim lock or mobile connection not working?

[50g]

Have an used Pixel 5 here which was labeled as sim locked (carrier unknown ). I'm not sure if it really has sim lock or if the mobile connection is defective. When I insert my SIM it asks for the PIN and then the correct carrier is shown under network settings - there is no signal however.

How can I make sure it has sim lock and it's not a HW defect?

If it's locked - is there a way to find out the carrier which it is locked by?

 

[50g]

More general - how is a sim lock indicated to the user when inserting a sim from another provider?

 

[50g]

I've sent the phone to google for repair (Connectivity problem). They stated that no defect was found which would support the sim lock theory. Is there a way to know for sure?

 

[swangjang]

If Google Repair team says there are no defects (assuming the team that handled it were competent), then it most likely is a carrier locked phone. I've never used a locked phone before so I'm not sure what to look for but if you can find out which carrier it's locked to, you could try inserting that carrier's sim card?
If you get a signal, then swap out the sim card to a different carrier and if it doesn't work, then it's definitely locked.

 

[50g]

I don't know which carrier it could be looked to and how to find that out. When I enter the IMEI at the start of the repair process in the google store the device is identified as "Pixel 5 (128 GB, Just Black, without SIM-Lock)".