I am on a work phone plan on AT&T using an iPhone 7. Since it's a business plan in my employer's name (I can't personally order phones through it), I used my parents account info and ordered an iPhone X through Verizon. From reading threads last week (that I can no longer find) I am under the impression I can take out the Verizon SIM as soon as the new phone arrives, before I turn on the iPhone X, and put the existing AT&T SIM in its place - and I will be good to go once I turn the phone on. Can anyone confirm if this will work as expected? Do I need to inform AT&T somehow (or talk to my work IT department) or should the new iPhone X just start working with AT&T since my existing SIM works? Appreciate any help. Thanks.