new ohone

[Melchilds]

Got a new phone same number but it's come with new sim do I use the new or the old

[jeffkinn]

If the old and new phones use the same size sim card you can continue to use the old one. 

You only need to change sim cards if you need a different size sim card.

[BandOfBrothers]

Another reason to change SIM card is if your moving to a 4G SIM card to use a 4G Tariff as older SIM cards are 3G compliant.

If your new phone takes a different size then perform the sim swap via the online site.