If you think for one minute they won't go to court for $1500 you are woefully ignorant of the realities of the collection business. And $1500 is if the 2 iP6+ were both only 16GB each!
The collection agency simply files in small claims court. Most of the time the debtors don't show and they get a default judgment for the price of the small claims court filing fee. It is ridiculously simply to write up a complaint for an outstanding debt like that - they use forms and just insert the creditor's name, debtor's name and the amount owed. And the small claims court filing fees are cheap.
You are just plain old wrong on that. They don't hire attorneys as I stated - they sell the debt to a collection agency. You don't know what you are talking about.
TMobile would not be coming after you. The collection agency who purchased the debt from TMobile will and they for sure will come after you for the money. That is the business they are in.
Do you work in the collection/debt/credit field?