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I work for a carrier. 5G is complicated so the system is designed to be accommodating. To get 5G speed improvements there are a couple requirements.
1) Have a 5G compatible smart phone. There are 2 different types of 5g and not all 5g phones can do both.
2) Have a plan or contract with a carrier that support 5G. Your old plan probably needs an update.
2.5) Rarely phones can be provisioned incorrectly so if for whatever reason you have some obscure and rare 5g compatible device the network might not automatically recognize it as 5g capable and you will have to call your carrier.

5G is a group of technologies not simply one new “breakthrough” so there are probably always going to be limitations for your specific hardware. Carriers will incentivize you to get a new SIM card because there are security improvements on the newer gen and the last gen of SIM cards has lasted 20 years. If the carriers are going to phase out 4g in the next decade or 2 they are going to have to start replacing these sims ASAP.

Tldr:Your 10 year old sim will get you that juicy 5g logo/speed on your iPhone 12.

I’m rocking a 5 year old Verizon sim and an att esim. Both give me 5G.
 
I work for a carrier. 5G is complicated so the system is designed to be accommodating. To get 5G speed improvements there are a couple requirements.
1) Have a 5G compatible smart phone. There are 2 different types of 5g and not all 5g phones can do both.
2) Have a plan or contract with a carrier that support 5G. Your old plan probably needs an update.
2.5) Rarely phones can be provisioned incorrectly so if for whatever reason you have some obscure and rare 5g compatible device the network might not automatically recognize it as 5g capable and you will have to call your carrier.

5G is a group of technologies not simply one new “breakthrough” so there are probably always going to be limitations for your specific hardware. Carriers will incentivize you to get a new SIM card because there are security improvements on the newer gen and the last gen of SIM cards has lasted 20 years. If the carriers are going to phase out 4g in the next decade or 2 they are going to have to start replacing these sims ASAP.

Tldr:Your 10 year old sim will get you that juicy 5g logo/speed on your iPhone 12.

I’m rocking a 5 year old Verizon sim and an att esim. Both give me 5G.
Also to note. In the states our 5g networks still use 4g for a lot of backend things and for phone calls. Stand-alone 5g networks in the future could require the newer sim when 4g is phased out.
 
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