Following the modest upgrades AT&T announced to its mobile plans yesterday, both T-Mobile and Sprint have hit back with new ‘unlimited’ plans.

T-Mobile has replaced all its plans with a single one called T-Mobile One.

As with all carrier plans, there are some caveats in the small-print …

First, the headline rate of $40 per line applies only if you’re buying four lines for a total of $160/month. If you want a single line, that will cost you $70/month.

Second, Recode notes that video on the plan is capped at standard-definition quality – if you want to watch HD video, that will cost you an extra $25/month, so that headline rate of $40 more than doubles in price to $95/month.

Third, the company’s Binge On deal already gave unlimited SD video for many popular services, so the switch to all-you-can-eat data may not make much real-life difference.

Sprint is a little cheaper at $60/mo, but also limits not just video but also music and gaming to unspecified ‘optimized’ rates. A two-line deal is available for $100/mo, reducing the per-line cost to $50/mo, while each extra line costs $30/mo. There’s no add-on option available for faster video. As with T-Mobile and AT&T, both talk-time and texts are unlimited.

Both deals compare favorably to AT&T’s new plans for heavy data users. In particular, while AT&T claims to now have a ‘no overages’ policy, the small-print states that your data speed is reduced to just 2G speeds once you hit your limit – which may have nostalgia appeal for those who want to go back in time to a first-gen iPhone in 2007, but is otherwise worthless.

Photo: Reuters/Brendan McDermid