What happens if you put a 5G Sim in a 4G phone?

Re: Can I buy a 5G sim deal for my 4G enabled phone? Yes, you can buy any SIM Plan for your phone .

SIM cards from the 3G UMTS network onwards are backwards and forward compatible, and mobile phones are backwards compatible. So, a 5G SIM card will work in a 4G phone , but will only allow you to access 4G, 3G and 2G networks if used in a 4G phone.

The truth is that 5G is not an entirely new network — it’s just added on top of the 4G network. So your 4G phone will keep working just fine and you’ll only have to upgrade if you want 5G’s blazing speed.