He wouldn't break even after 4 years, though. Nowhere near close to it, actually.
Keep in mind that it's for 2 lines. So, with the T-mobile prices, that's $1300 up-front for two iPhone 5's(the iPhone's $650 MSRP is about average for carrier-subsidized phones), versus $400 for the two phones through ATT. So that means, over 48 months, for the T-mobile plan to be better, he needs to save $900 over that period. That comes out to $18.75 per month.
The $5 he saves per month, after 48 months, would be $240. That's half of the subsidized cost difference for one phone, but his plan has 2 phones. In that case, the ATT plan would have saved him $600 ($6400 for ATT for 2 $200 iPhones and $125/month for 48 months vs $7060 for 2 $650 phones and $120/month for 48 months).
In fact, at that per month price difference, it would take 15 years to make up the difference between the ATT subsidized and non-subsidized T-mobile.
Keep in mind that it's for 2 lines. So, with the T-mobile prices, that's $1300 up-front for two iPhone 5's(the iPhone's $650 MSRP is about average for carrier-subsidized phones), versus $400 for the two phones through ATT. So that means, over 48 months, for the T-mobile plan to be better, he needs to save $900 over that period. That comes out to $18.75 per month.
The $5 he saves per month, after 48 months, would be $240. That's half of the subsidized cost difference for one phone, but his plan has 2 phones. In that case, the ATT plan would have saved him $600 ($6400 for ATT for 2 $200 iPhones and $125/month for 48 months vs $7060 for 2 $650 phones and $120/month for 48 months).
In fact, at that per month price difference, it would take 15 years to make up the difference between the ATT subsidized and non-subsidized T-mobile.