I have a spare EE iPhone 6 and my work phone (o2) needs replacing, can I convert my EE phone into an O2 phone until work replaces my phone?

I have a spare EE iPhone 6 and my work phone (o2) needs replacing, can I convert my EE phone into an O2 phone until work replaces my phone?

Read more: https://iphoneus.org/faq/i-have-a-spare-ee-iphone-6-and-my-work-phone-o2-needs.html