Copied from /u/Ethrem on Reddit

7/25/2021 - small update to Verizon and ATT

8/6/2021 - removed priority data from Spectrum Mobile

10/29/2021 - Cricket has revamped their plans, updated priority levels. The $60 Unlimited More plan is now prioritized. Red Pocket GSMA no longer has a speed throttle on LTE or 5G. Pure Talk has been reported to not have one anymore either.

11/5/2021 - It seems that some people still have the 75Mbps speed cap on Red Pocket GSMA so YMMV. My own testing over the last month with a GSMA SIM found no such cap as I got speeds consistently in excess of 100 and even 200Mbps.

12/31/2021 - Removed Total Wireless from QCI 8. Nobody has furnished me with any proof of QCI 8 and some people have confirmed that their Total runs slower than their Verizon postpaid which confirms deprioritization.

01/12/2021 - Updated to add Boost Mobile’s ATT plans as deprioritized.

03/24/2022 - Updated to reflect that 5G devices on US Mobile Super LTE and Xfinity Mobile get priority data now.

4/10/2022 - Added SafeLink to ATT’s QCI 9 list.

9/14/2022 - Updated Visible info.

10/28/2022 - Big update, too much to list.

2/26/2023 - Another big update.

3/21/2023 - Xfinity Mobile has added priority data to Unlimited Plus.

4/6/2023 - Updated to reflect that mobileX has priority data on all plans.

This is a complex topic that pops up a lot so I thought that I would organize all of the available info in one place. One of the key differentiating factors between postpaid, prepaid, and MVNO services is data prioritization. Basically carriers manage the congestion on their networks by assigning a different QCI class to different types of traffic. For our purposes, we will only be looking at QCIs 6, 7, 8, and 9 but there are higher priorities that exist for things like phone calls that will be universal across all of a carrier’s plans. Higher numbers are lower priority. An important thing to note is that deprioritization is not a throttle; it only matters when the network is congested. If nobody else is using the network in your area, you’ll get the full speed that can be provided. Your QCI affects not just your speed but your latency on the network. It is not unusual to see priority data with around 20-50ms latency while someone who is deprioritized is getting 100-150ms at the same time despite both plans posting high speed test results because the prioritized traffic gets to go first, just something else to be aware of.

Verizon Verizon only uses two QCIs, 8 and 9. This means you’re either in the fast lane or the slow lane with them.

QCI 8 is assigned to postpaid plans (other than 5G Start and Welcome Unlimited which are deprioritized), Xfinity Mobile’s By The Gig plan, Xfinity Mobile’s Unlimited Plus plan, Xfinity Mobile’s Unlimited Premium plan, mobileX, and TracFone (as well as SafeLink). Additionally, US Mobile’s Warp 5G SIM offers priority data on 5G devices on all plans and Visible+ is QCI 8 until 50GB is used. Verizon has also finally added premium data to their own branded prepaid - 50GB on the top Premium Plus plan.

QCI 9 goes to literally everything else - branded prepaid besides the Premium Plus plan, Visible plans besides Visible+, US Mobile Warp 5G on LTE devices, Mobi, and all of the other prepaid MVNOs that use Verizon’s network will be assigned this QCI class. In addition everyone who uses their data bucket is moved to QCI 9 as well so you end up competing with all of Verizon’s heavy data users. Verizon’s network is spectrum-starved in many areas so its not unusual to see complaints about Verizon’s policies here.

ATT AT&T has shifted their policies a bit. They use 6, 7, 8, and 9 but only 7, 8, and 9 are available for consumer grade plans.

QCI 7 is only on ATT’s postpaid Unlimited Premium plan. This is their top of the line, most expensive, consumer postpaid plan. If you demand the best performance and you’re not eligible for FirstNet or a business plan, this is the plan you want.

QCI 8 is assigned to the majority of ATT’s plans as well as their own branded prepaid (other than the Unlimited plan), the Cricket More plan (their most expensive), and plans offered by H2o, Consumer Cellular, and PureTalk.

QCI 9 is assigned to ATT’s Unlimited prepaid and Unlimited Starter postpaid plans, as well as all plans once their data bucket is exhausted. Unfortunately most AT&T MVNOs are now QCI 9 as well. This includes Red Pocket and Boost. Many that used to be QCI 8 will need to be tested but probably should be assumed to be QCI 9 by default.

T-Mobile T-Mobile uses QCI 6, 7, 8, and 9. They are generally considered to be only a bit behind ATT in their traffic deprioritization policies for MVNOs.

QCI 6 is applied to all of T-Mobile’s postpaid and prepaid plans (except for Essentials) and Google Fi which also has QCI 6 as well. This means if you want the absolute best from T-Mobile, you want to get a plan directly from them. Even their cheap $10 prepaid 1GB Connect plan has priority data.

QCI 7 is applied to T-Mobile’s Essentials plan as well as all MVNOs (besides Google Fi) such as Mint, Metro By T-Mobile, US Mobile GSM LTE, and Tello.

QCI 8 is believed to be for any hotspot usage on a consumer plan.

QCI 9 is for their home internet service (yes, its deprioritized to last network priority) and all plans once their data bucket is exhausted.

I will be doing my best to keep this up to date. Feel free to let me know if I have missed anything or if I should add anything.

I first learned about data priority reading on Coverage Critic and from posts here and elsewhere. If you wish to test your QCI class yourself, you can follow this guide if you have a rooted Android phone.