Verizon Wireless will start throttling video streams to resolutions as low as 480p on smartphones this week. Most data plans will get 720p video on smartphones, but customers won't have any option to completely un-throttle video.

1080p will be the highest resolution provided on tablets, effectively ruling out 4K video on Verizon's mobile network. Anything identified as a video will not be given more than 10Mbps worth of bandwidth. This limit will affect mobile hotspot usage as well.

Verizon started selling unlimited smartphone data plans in February of this year, and the carrier said at the time that it would deliver video to customers at the same resolution used by streaming video companies. "We deliver whatever the content provider gives us. We don't manipulate the data," Verizon told Ars in February.

That changes beginning on Wednesday, both for existing customers and new ones. The changes were detailed today in an announcement of new unlimited data plans.

Starting August 23, Verizon's cheapest single-line unlimited smartphone data plan will cost $75 a month, which is $5 less than it cost before. The plan will include only "DVD-quality streaming" of 480p on phones and 720p on tablets. (Tablet data service is priced as an add-on to smartphone plans and costs $20 a month.)

Customers who buy a new unlimited data plan can get higher-quality video for an extra $10 per month. The higher video quality of 720p on phones and 1080p on tablets will be available on Verizon's "Beyond Unlimited" plan, which is $85 a month for a smartphone connection and another $20 for a tablet. Verizon says that with these resolutions, video quality should be about the same on the larger screens of tablets as it is on the smaller screens of phones.

If you're already a Verizon customer, your video resolution will be reduced to 720p on phones and 1080p on tablets whether you have a limited or unlimited data plan. Customers who purchase any Verizon limited plan in the future will see the same restrictions.

"Moving forward, HD video on all legacy plans will also match Beyond Unlimited's HD quality," Verizon said.

For postpaid customers, the 480p limit thus applies only to people on the new $75 unlimited plan. These customers get the benefit of avoiding overage charges and strict monthly caps, but they won't get the same video quality as customers who either have a limited data plan or splurge for the "Beyond Unlimited" plan. The 480p limit also applies to prepaid plans.

Verizon apparently won't be converting videos to lower resolutions itself. Instead, it will set a bandwidth limit that video applications will have to adjust to. "We manage HD video throughput by setting speeds at no more than 10Mbps, which provides HD video at up to 1080p video," Verizon told Ars. The Mbps will presumably be lower than that in cases where Verizon limits video to 480p or 720p.

The 1080p limit will apply when customers use their mobile devices as hotspots, Verizon said. That means you won't be able to stream 4K video on a laptop by tethering the laptop to a Verizon-connected smartphone, for example.

"More than 96 percent of customers have not used 4K video," Verizon also told us.

Hotspot speed limits

The $75 plan's mobile hotspot service will top out at only 600kbps. The Beyond Unlimited plan will offer 15GB of 4G LTE hotspot speeds per month and reduce tethering speeds to 600kbps after that.

Customers who bought unlimited data earlier this year at the previous price of $80 per month will get the same video quality and high-speed tethering amounts as the Beyond Unlimited plan.

There is good news for businesses that want to equip employees with unlimited data. Previously, customers could only get up to 10 lines of unlimited data on Verizon. But Verizon will now let businesses buy unlimited data plans for as many employees as they want.

Here's a pricing chart from Verizon's announcement for the new plans available on Wednesday:

While Verizon's "unlimited" plans don't have overage fees for using too much data, customers who use more than 22GB a month may have their speeds reduced below other customers in areas with network congestion.

Preventing congestion

The video quality changes are apparently aimed at reducing or preventing congestion in Verizon's network. "We're doing this to ensure all customers have a great experience on our network since there is no visible difference in quality on a smartphone or tablet when video is shown at higher resolutions than 720p on phones and 1080p on tablets," the Verizon announcement today said.

"We're really managing our network in a way to be able to expand unlimited data to more people," Verizon marketing executive Angie Klein told Ars yesterday.

Testing firm OpenSignal recently found that Verizon's "average LTE download test fell 2Mbps to 14.9 Mbps" in the months after its launch of unlimited data. T-Mobile CEO John Legere also claimed that the Verizon and AT&T networks "seem to be choking after we forced them to go unlimited." (T-Mobile also throttles video on unlimited plans by default but lets customers activate HD video by paying extra.)

RootMetrics, another testing firm, has consistently found that Verizon's network offers better overall reliability and speed than its competitors. "Our network has never been stronger," Klein said. "RootMetrics confirmed it again last month."

Verizon tested video throttling last month

Verizon signaled that it might start throttling video streams by default last month when it conducted a temporary test of a video optimization system that capped video speeds at 10Mbps. (Some YouTube users said they were able to bypass the limits by using a VPN service.) Advocacy group Free Press alleged that Verizon violated net neutrality rules by throttling video applications on its mobile network, but Verizon denied breaking any rules.

Last month, Verizon said:

Current net neutrality rules clearly state that providers may employ reasonable network management practices to ensure that their networks and services run efficiently and work well for their customers... Video optimization is a non-discriminatory network management practice designed to ensure a high quality customer experience for all customers accessing the shared resources of our wireless network.

The FCC allowed similar video throttling systems to continue even under former Chairman Tom Wheeler, who instituted the net neutrality rules in 2015. The FCC's current chairman, Ajit Pai, has proposed eliminating the rules.