A member of my family plan is eligible for an upgrade but does not wish to change their device. If we use the upgrade discount to purchase a new phone anyway, will I be able to use it as a second phone by simply switching my SIM card when desired?
The reason I ask is that I currently have a Lumia 920 and I would like to try out the HTC One for a while without giving up my current phone. If I like it, I'll keep it; if not, I'll sell it. I understand that the upgraded line would still be bound to the new two year contract.
Yes, you can do this. The only thing that my have to change is your data plan type, but I think that the data plan is the same for Windows Phones and for Android phones. Try it and see if the data works. If it does, then you're fine. If it doesn't, call in to customer service and have them change the data plan type. The cost is the same across the data plans.