Q: How do I sync my old mobile number to my new iphone

Transfer content from an iPhone, iPad, or iPod touch to a new device - Apple Support

Contact your carrier. They will step you through getting your new phone using the old number and removing the old phone from that number.

Hi

Have you had number transfered to you simcard .

Go to settings phone icon next to messages click on that change phone number

Top of page .

Cheers

Brian