QCI (QoS Class Identifiers) Explained

Quality of service class identifiers (also called QCI values) are used to indicate how traffic should be handled on LTE networks.1 Without getting too technical, QCI values indicate a certain priority level for traffic on a network.

Most data use is associated with QCI values between 6 and 9. Within that range, lower QCI values are associated with higher-priority service on a given network.

Some services, like voice calls and IMS signaling, may be associated with QCIs below 6. These low QCIs typically confer especially high priority and guaranteed bit rates. For a technical treatment of QCI values, see the 3GPP publication on Policy and charging control architecture.

Observed QCI Values

The lists below show QCI values observed with regular data use.2 The appendix includes screenshots and additional information about each test.3


AT&T’s Network

AT&T:

  • Unlimited Starter – QCI 9
  • Unlimited Extra – QCI 8
  • Unlimited Elite – QCI 7

After running through my allotment of Premium Data on the Unlimited Extra plan, data use transitioned to being associated with a QCI of 9. I expect a similar transition occurs for subscribers on the Unlimited Elite plan.

Cricket wireless:

  • Limited-data plan – QCI 8

T-Mobile’s network

T-Mobile:

  • Essentials – QCI 7
  • Magenta – QCI 6
  • Connect – QCI 6

Google Fi:

  • Standard plan – QCI 6

Mint Mobile:

  • Standard plan – QCI 7

Verizon’s network

Verizon:

  • Play More Unlimited – QCI 8
  • Do More Unlimited – QCI 8
  • Get More Unlimited – QCI 8

After running through my allotment of Premium Data on the Play More Unlimited plan, regular data use was associated with a QCI of 9. I expect the same transition occurs for subscribers on the Do More Unlimited and Get More Unlimited plans.

Total Wireless:

  • Standard plan – QCI 9

Visible:

  • Standard plan – QCI 9

Xfinity Mobile:

  • By-the-gig plan – QCI 8
  • Unlimited plan – QCI 9

Standardized QCI characteristics

The following table is a modified and abbreviated version of what appears in the 3GPP standards. Carriers may not always use QCI values is a way that’s entirely consistent with the standards.4

QCIResource TypePriority LevelPacket Delay BudgetPacket Error Loss RateExample Services
1Guaranteed Bit Rate (GBR)2100 ms10-2Conversational Voice
2GBR4150 ms10-3Conversational Video (Live Streaming)
3GBR350 ms10-3Real Time Gaming; V2X messages
4GBR5300 ms10-6Non-Conversational Video (Buffered Streaming)
65GBR0.775 ms10-2Mission Critical user plane Push To Talk voice (e.g., MCPTT)
66GBR2100 ms10-2Non-Mission-Critical user plane Push To Talk voice
67GBR1.5100 ms10-3Mission Critical Video user plane
75GBR2.550 ms10-2V2X messages
5Non-GBR1100 ms10-6IMS Signalling
6Non-GBR6300 ms10-6Video (Buffered Streaming); TCP-based (e.g., www, e-mail, chat, ftp, p2p file sharing, progressive video, etc.)
7Non-GBR7100 ms10-3Voice; Video (Live Streaming); Interactive Gaming
8Non-GBR8300 ms10-6Video (Buffered Streaming); TCP-based (e.g., www, e-mail, chat, ftp, p2p file sharing, progressive video, etc.)
9Non-GBR9300 ms10-6Same as above
69Non-GBR0.560 ms10-6Mission Critical delay sensitive signalling (e.g., MC-PTT signalling, MC Video signalling)
70Non-GBR5.5200 ms10-6Mission Critical Data (e.g. example services are the same as QCI 6/8/9)
79Non-GBR6.550 ms10-2V2X messages
80Non-GBR6.810 ms10-6Low latency eMBB applications (TCP/UDP-based); Augmented Reality

Further Notes On QCI Values

  • The consequences of a service’s QCI value will depend on the QCI values of other services operating on the same network. While a QCI of 7 appears to be indicative of high-priority data on AT&T’s network, a QCI of 7 appears to be indicative of relatively low-priority data on T-Mobile’s network.
  • Network operators might sometimes broadcast QCI values that aren’t accurate.5
  • I expect T-Mobile reserves a QCI of 8 for mobile hotspot use, but I haven’t confirmed that in a test.
  • I don’t know how prioritization works on 5G networks. I’m hoping to get a handle on that as 5G becomes ubiquitous.

Appendix

Carriers using AT&T’s network (expanded)

AT&T

Unlimited Starter

I found a QCI of 9 for regular data use on AT&T’s Unlimited Starter plan on 8/31/2020.
Test result showing a QCI of 9

Unlimited Extra

I found a QCI of 8 for regular data use on the Unlimited Extra plan on 9/2/2020. I ran the test when I had Premium Data available.
Test result showing a QCI of 8

On 11/11/2020, I ran a test when I no longer had Premium Data available. I found a QCI of 9 for regular data use.
Test result showing a QCI of 9

Unlimited Elite

I found a QCI of 7 for regular data use on the Unlimited Elite plan on 11/13/2020. I had Premium Data available when I ran the test.
QCI test showing a result of 7

Cricket Wireless

I found a QCI of 8 for regular data use on a non-unlimited Cricket plan on 5/17/2020.

Test result showing a QCI of 8 on a non-unlimited Cricket Wireless plan

Carriers using T-Mobile’s network (expanded)

Google Fi

I found a QCI value of 6 for regular data use on Fi’s service on 9/17/2019.6

T-Mobile

Essentials

I found a QCI of 7 for regular data use on a T-Mobile Essentials plan on 9/3/2020.
Test result showing a QCI of 7

Connect

I found a QCI value of 6 for regular data use on a T-Mobile Connect plan on 5/14/2020.

A test run on a T-Mobile Connect plan showing a QCI of 6

Magenta

I found a QCI value of 6 for regular data use on T-Mobile’s Magenta plan on 11/11/2020.

QCI test showing a QCI of 6

Mint Mobile

I found a QCI value of 7 for regular data use with Mint Mobile’s service on 9/17/2019.

Carriers using Verizon’s network (expanded)

Verizon

Play More Unlimited

I found a QCI of 8 for regular data use on the Play More Unlimited plan on 7/2/2020. I had not used up my Premium Data allowance when I ran the test.

Screenshot of a test result showing a QCI value of 8

After running through my Premium Data, I found a QCI of 9 on 7/3/2020.

QCI test result run after Premium Data allotment was used up. Screenshot shows a QCI of 9.

Do More Unlimited

I found a QCI of 8 for regular data use on the Do More Unlimited plan on 9/2/2020. I had Premium Data available when I ran the test.

Get More Unlimited

I found a QCI of 8 for regular data use on Verizon’s Get More Unlimited plan on 10/21/2020. I had Premium Data when I ran the test.

QCI test showing a QCI of 8

Total Wireless

I found a QCI of 9 for regular data use with Total Wireless on 6/2/2020.

QCI test for Total Wireless showing a QCI of 9

Visible

Stetson Doggett found a QCI of 9 with Visible on 7/21/2020.

Test showing a QCI of 9

Xfinity Mobile

I found a QCI of 9 for regular data use on a second-generation Xfinity Mobile unlimited plan on 5/19/2020.

Test showing a QCI of 9 on a second-generation Xfinity Mobile unlimited plan

I found a QCI of 8 for regular data use on a third-generation by-the-gig plan on 7/3/2020.

Screenshot of a test result showing a QCI of 8 on a third-generation Xfinity Mobile by-the-gig plan

Carriers using Sprint’s network (expanded)

Sprint

Kickstart

Stetson Doggett found a QCI of 6 with Sprint Kickstart on 7/21/2020.

Test showing a QCI of 6

Footnotes

  1. Other (often related) mechanisms include guaranteed bit rates, maximal bit rates, and allocation and retention priority. The excerpt below comes from page 51 of 3GPP TS 23.203 V16.1.0:
    “The service level (i.e., per SDF or per SDF aggregate) QoS parameters are QCI, ARP, GBR, and MBR.”
  2. When I say “regular data use,” I’m excluding voice calls, IMS signaling, and some atypical forms of data use.
  3. I’m building a database of QCI values. I share details about how QCI tests can be conducted on another page. If you’d like to contribute test results, please get in touch.
  4. Based on Table 6.1.7-A: Standardized QCI characteristics from 3GPP TS 23.203 V16.1.0.
  5. In a Reddit thread, user chrisprice suggested that some network operators broadcast QCI values that aren’t accurate. I think the user overstated his or her case and said some inaccurate things in the discussion, but I still take the possibility seriously. I’ve seen the same user demonstrate a deep understanding of the cellular industry in other conversations.

    The user chrisprice also raised the possibility that mechanisms other than QCI values may in some cases be used to manage traffic. An example involving AT&T dropping DNS links was shared in the discussion. I asked Roger Enter, an industry analyst, about the topic. He expressed skepticism about the idea that mechanisms other than QCI values are regularly used to prioritize traffic.

  6. I did this using a device that was compatible with Fi but not designated “Designed for Fi.”