Verizon said on Sunday it will launch an unlimited LTE data plan, called Verizon Unlimited, on Monday. The plan starts at $80 a month for one line or $45 a line for a group of four on smartphones or tablets. Both new and existing subscribers can sign up.

The move marks the first time in more than five years that Verizon, the nation's largest carrier in terms of total subscribers, will have an unlimited offering. The carrier recently started forcing heavy users who had stayed on old unlimited plans to move to new offerings.

Executives at the company have downplayed the need for unlimited plans in recent months, too, though the carrier started allowing customers last fall to pay for unlimited usage in 30- and 60-minute increments.

The new plan comes on the heels of other renewed and aggressive pushes into unlimited data from rival carriers, most notably T-Mobile, which has grown in recent months while Verizon's mobile division has slowed, and in August replaced all its existing mobile plans in favor of one unlimited offering called T-Mobile One.

T-Mobile's plan has faced criticism, however, for downgrading all video streams to a non-high-definition resolution unless subscribers pay an extra $15. It also does not allow subscribers to access LTE speeds when using their phones as a mobile internet hotspot by default.

Verizon appears to be directly going after those complaints. The carrier says its unlimited plan allows users to stream video at an "HD" resolution and that it includes up to 10 GB of LTE mobile hotspot data before cutting that to 3G speeds. The carrier did not specify whether it allows videos to stream above a 720p resolution, the minimum threshold for HD video, though.

Verizon says the plan also provides unlimited calling and texting to Canada and Mexico, along with 500 MB a day of LTE data in those countries. A $10-a-day pass allows for that same amount of data outside of North America.

The Verizon logo is seen on the side of a truck in New York Thomson Reuters

Verizon is keeping other tiered data plans available alongside the new unlimited plan, including a 5 GB a month offering, as well as its S, M, and L plans. Currently, those plans go from $35 a month for 2 GB of LTE data to $70 a month for 8GB of data. Verizon previously offered plans with larger data buckets on its site, but those will now only be available in stores or over the phone.

The $80-a-month starting point makes Verizon's unlimited plan costlier than T-Mobile One, which starts at $70 a month for a single line, and Sprint's unlimited data plan, which normally costs $60 a month. But it is less expensive than AT&T's unlimited plan, which starts at $100 a month and only comes bundled with a subscription to the carrier's DirecTV or U-Verse services.

Like some of those rival offerings, Verizon's plan requires you to enroll in auto-billing to get the lowest price possible. While its four-line group plan is $45 a month ($180 total), Verizon says a two-line plan costs $70 a month per line ($140 total), while a three-line plan costs $54 a month per line ($162 total).

T-Mobile US CEO John Legere speaks at the 2013 Consumer Electronics Show. David Becker/Getty Images

Verizon is still generally seen as having the fastest and most widely available network in the US, though a recent study from the mobile-analytics firm OpenSignal found that T-Mobile has largely caught up when it comes to average speeds.

In any case, Verizon's new plan comes with the same caveat as every other unlimited offering: It's not technically unlimited. Verizon says any line that uses more than 22 GB of mobile data in a month may see its data "prioritized" behind other customers in times of network congestion. T-Mobile, Sprint, and AT&T warn of similar limits, too.

Still, that allotment should be enough for most people and would seem to give Verizon a plan it can sell to hungrier users in an increasingly data-heavy time.