How to remove sim
Is it always necessary to remove sim when switching to a new phone and does to new phone keep the old SIM card?
It is up to you if you wish to switch. New iPhones that are set to a carrier will come with a SIM, and you can use that one so long as you have the carrier activate it. If you purchase your iPhone from your carrier, it will come with a SIM and it will be activated when you make the purchase. However if you get a SIM free phone from the Apple Store, it will not.