Virgin Mobile USA goes iPhone-exclusive, promises first year of unlimited plan for $1

The $1 unlimited deal is available to new customers buying an iPhone, along with existing subscribers paying to upgrade, the carrier said. After the first year the plan will cost $50 per month, with mandatory AutoPay.

There are additional restrictions. Some forms of data, for instance, are being "mobile-optimized" — video streams at about 480p resolution, while music is limited to 500 kilobits per second. "Cloud gaming" is capped at 2 megabits per second.

After 23 gigabytes are used in a month, customers may find their bandwidth throttled in times and places with network congestion. Subscribers are at risk of losing service altogether if off-network roaming exceeds 800 voice minutes or 100 megabytes.

Paying an extra $5 per month allows unlimited global texting, and unlimited calls to Canada and Mexico. A $10 add-on includes everything in the $5 bundle, plus unlimited landline calls to over 70 countries, 200 voice minutes to "select" cellphones in over 50 countries, and lower per-minute rates to some 200 locations.

People enrolled in Inner Circle should also get perks from various Virgin-related businesses, such as a bonus Virgin Atlantic ticket when booking a round-trip fare to the U.K.

iPhone prices range from $279 for a 32-gigabyte iPhone SE through to $969.99 for a 256-gigabyte 7 Plus. The carrier is also selling a 32-gigabyte iPhone 6, albeit for $319. Orders made today will ship June 27.