Samsung A15 not working with my Public Mobile SIM card

[Balsam]

Hello community fellows,

I just bought a new Samsung A15 (a 5G phone) to replace my old phone but it doesn't recognise my SIM card which is on the cheapest $15/month plan with 3G speed for data. The Settings -> Connections -> Mobile networks -> Network operators shows "No service", and Network mode has these 5 selections:

• 5G/LTE/WCDMA/GSM(auto connect)
• LTE/WCDMA/GSM(auto connect)
• WCDMA/GSM(auto connect)
• WCDMA only
• GSM only

But I can't change the selection. It always stay on the first one no matter which one I clicked. 

So without mobile network service, obviously I can't make a phone call and receive a phone call, and can't send out text messages. But weird thing is, I'm able to receive text message and the message telling me that I have a voice mail.

Does anyone know why it doesn't recognise my SIM card (the card itself is fine, works on my old phone)? Is there any setting I need to change on the phone to make it work?

Thanks,

[Balsam]

Thank you! Turning it off and back on fix the problem. I should have tried it before asking for help although I don't know why it can fix it.

[BKNS27]

@Balsam 

Try resetting the network setting and see if that works.

[hairbag1 · Accepted solution]

@Balsam 

try shutting phone off, remove sim...replace sim carefully to confirm it's it place correctly...restart.