Hi, For some reason my iPhone X did not activate automatically on ATT after I turned it on. My iPhone 6s+ is still primary phone. I went to this link to activate X https://www.att.com/shop/easyactivate/coamoffdevice/deviceinfo.html I am thinking of returning the X and would like to know if I can reactivate the 6s+ online or will I have to call ATT? Cam u reactivate an older phone or will ATT need to send a new SIM for each reactivation. I am asking as I might be travelling internationally in the near future. Thanks.