u mean sim card , if so there is change phone number option .use that

You can simply transfer your account to the new number you will find the option in settings

that's when login comes in

If u didn't change ur sim card,i mean number u can type ur number when it ask u your number so ur data will be backup

If you have to replace your phone number or the phone it self??

Log out

Hmu

All your datas are saved on the cloud as long as you don't change the sim card so no worries you can replace the phone without losing your status whatsoever