Which phone do I put the sim card in when upgrading & using smart switch?

[AC Question]

Sorry to maybe appear dim but which phone do I put the sim card in when upgrading & using smart switch? Do I leave my sim in the old phone for the time being?

 

[the tall guy]

Hi, put it in your new phone. The "smart switch" process moves a lot more than just contacts (the only thing stored on a sim)