Throttling and Prioritization Explained

Throttling

Throttling occurs when data transfer is capped at a specific speed. Often, caps apply to all data usage. For example, as of April 2019:

  • Mint Mobile subscribers who’ve used up their allotted high-speed data have speeds throttled to a maximum of 128kbps.1

  • Visible generally caps data speeds at 5 megabits per second (Mbps).2

In my experience, carriers are usually transparent about (a) the existence of throttling on data speeds and (b) the speeds that subscribers will be capped at.

Carriers may also throttle specific applications or types of traffic. Targeted throttling often affects video streaming. For example, streaming video is limited to 480p quality on Verizon’s prepaid plans.3

Prioritization

Prioritization can affect the quality of service that subscribers receive when networks are congested. Rather than treating all users of a congested network equally, network operators generally prioritize some users’ activities over other users’ activities. Unlike throttling, prioritization is not going to affect an individual’s wireless experience when a network is not congested.

As a general rule, subscribers on more expensive, postpaid plans are likely to be prioritized over other subscribers. However, that general rule leaves out a lot of nuances. Sometimes prioritization differences may exist within a single class of customers. Postpaid customers that use excessive amounts of data on unlimited plans may have their network access deprioritized. Here are a few examples of prioritization policies affecting those that subscribe to Verizon’s postpaid unlimited plans:4

  • GoUnlimited: “In times of congestion, your data may be temporarily slower than other traffic.”
  • BeyondUnlimited: “After 22 GB/line, in times of congestion, your data may be temporarily slower than other traffic.”
  • AboveUnlimited: “After 75 GB/line, in times of congestion, your data may be temporarily slower than other traffic.”

In the weeds

Carriers aren’t usually upfront about the details of their prioritization procedures.5 I’ve seen a number of people express the view that networks regularly use several prioritization tiers. According to this view, network operators assign prioritization levels based on how profitable different types of subscribers are: postpaid subscribers are the highest priority, followed by prepaid subscribers, with subscribers to mobile virtual network operators (carriers that use networks owned by other companies) receiving the lowest priority.6 I don’t think this view is quite right. I explain my best guesses about each major network’s prioritization polices in the following articles:

Footnotes

  1. “When your data is reduced, it will be reduced to 128 kpbs.”
    From a Mint Mobile support response on the Mint Mobile community forum (archived here).
  2. “We’re built for life on the go, so instead of giving you extra speed you don’t need (and making you pay for it), you get unlimited data at speeds up to 5 Mbps.”
    From Visible’s FAQ as of 4/24/2019 (archived here).
  3. “DVD-quality streaming (up to 480p) on smartphones.”
    From Verizon’s prepaid page on 5/27/2019.
  4. These examples come from Verizon’s unlimited plans web page as of 4/26/2019.
  5. In my experience, carriers often mention that deprioritization is a possibility, but they rarely share enough details for consumers to really assess how significant an effect deprioritization is liable to have on their experience. As of April 2019, I’ve never seen a third-party company try to make a rigorous, empirical assessment of differences in prioritization between services.
  6. This is a view I’ve seen expressed multiple times in Reddit’s NoContract community.

3 thoughts to “Throttling and Prioritization Explained”

  1. It took me a while to figure out why my device was reporting a full 5g signal connection but I was unable to get ANY data. Then I discovered some fine print on TMobile. Now I know what’s going on and I think it’s B.S. and I don’t want to do business with companies that support this business model. 🤬 Fat cat CEOs gotta go.

  2. This article was fabulous but I believe there are more than two levels of prioritization with most of the carriers.
    For example, I have two Verizon iPhones and two Verizon iPads, all on a Postpaid plans (DoMore unlimited). All are LTE only devices.
    The cell phones consistently run faster data than the iPads (often 2 – 3 times the speeds).
    But when network congestion is apparent, the iPads become completely unusable (download rates drop to .03 – .06 MB/s whereas the iPhones slow to maybe 2 – 6 MB/s at the same time in the same locations.
    That proves to me that Verizon is prioritizing phone internal data over other devices such as tablets and hot spots.

    1. Hi Mark,

      It’s possible devices like iPads are prioritized behind most phones on postpaid plans–I haven’t ever run a QCI test on an iPad. That said, I think worse case scenario, iPads would be at the same level as other low-priority services on Verizon’s network (e.g., prepaid plans).

      It’s also possible your iPads have different modem/connectivity capabilities than your phones. In that situation, all the devices could have the same priority level, but receive different speeds based on which bits on Verizon’s spectrum they happen to be using.

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