AT&T is giving away HBO with its unlimited plan as a response to fervent competition from T-Mobile and Verizon, and its increasingly close ties with its mobile and DirecTV divisions.

The company has announced that all AT&T Unlimited Plus customers will get access to HBO wherever it is available — through DirecTV Now or HBO Go — and that existing subscribers to the service through DirecTV will begin receiving it for free.

Customers who have Unlimited Plus but not HBO on DirecTV get a $25 monthly credit that can be put towards the service.

The move comes after both T-Mobile and Verizon have begun making it easier to watch content through wireless networks, either by zero-rating services like Verizon's Fios TV for mobile subscribers or, in the case of T-Mobile, zero-rating all video streams.

AT&T's unlimited wireless plan is currently the most expensive among the Big Four carriers, with one line beginning at $90 per month and two rounding up to $145 (with $20/month increases thereafter), but the company hopes that this HBO tie-in will bring more people into the fold.

More: Which unlimited plan should you buy?

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