Error message - "invalid number" when texting
I have a new Iphone 13 mini. I keep getting error messages when I try to text my friend. Other numbers work fine, but with this one person it doesn't. It keeps saying "Error Invalid Number. Please re-send using a valid 10 digit number." Of course I only had typed a 10 digit number, but the phone keeps adding 1 in front of the number as soon as I start to type the text. I have googled for answers but nothing has worked - so annoying!! I have been unable to send any texts successfully to this person.