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
- 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.
- Limited-data plan – QCI 8
- Essentials – QCI 7
- Magenta – QCI 6
- Connect – QCI 6
- Standard plan – QCI 6
- Standard plan – QCI 7
- 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.
- Standard plan – QCI 9
- Standard plan – QCI 9
- 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
|QCI||Resource Type||Priority Level||Packet Delay Budget||Packet Error Loss Rate||Example Services|
|1||Guaranteed Bit Rate (GBR)||2||100 ms||10-2||Conversational Voice|
|2||GBR||4||150 ms||10-3||Conversational Video (Live Streaming)|
|3||GBR||3||50 ms||10-3||Real Time Gaming; V2X messages|
|4||GBR||5||300 ms||10-6||Non-Conversational Video (Buffered Streaming)|
|65||GBR||0.7||75 ms||10-2||Mission Critical user plane Push To Talk voice (e.g., MCPTT)|
|66||GBR||2||100 ms||10-2||Non-Mission-Critical user plane Push To Talk voice|
|67||GBR||1.5||100 ms||10-3||Mission Critical Video user plane|
|75||GBR||2.5||50 ms||10-2||V2X messages|
|5||Non-GBR||1||100 ms||10-6||IMS Signalling|
|6||Non-GBR||6||300 ms||10-6||Video (Buffered Streaming); TCP-based (e.g., www, e-mail, chat, ftp, p2p file sharing, progressive video, etc.)|
|7||Non-GBR||7||100 ms||10-3||Voice; Video (Live Streaming); Interactive Gaming|
|8||Non-GBR||8||300 ms||10-6||Video (Buffered Streaming); TCP-based (e.g., www, e-mail, chat, ftp, p2p file sharing, progressive video, etc.)|
|9||Non-GBR||9||300 ms||10-6||Same as above|
|69||Non-GBR||0.5||60 ms||10-6||Mission Critical delay sensitive signalling (e.g., MC-PTT signalling, MC Video signalling)|
|70||Non-GBR||5.5||200 ms||10-6||Mission Critical Data (e.g. example services are the same as QCI 6/8/9)|
|79||Non-GBR||6.5||50 ms||10-2||V2X messages|
|80||Non-GBR||6.8||10 ms||10-6||Low 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.
Carriers using AT&T’s network (expanded)
I found a QCI of 9 for regular data use on AT&T’s Unlimited Starter plan on 8/31/2020.
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.
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.
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.
I found a QCI of 8 for regular data use on a non-unlimited Cricket plan on 5/17/2020.
Carriers using T-Mobile’s network (expanded)
I found a QCI value of 6 for regular data use on Fi’s service on 9/17/2019.6
I found a QCI of 7 for regular data use on a T-Mobile Essentials plan on 9/3/2020.
I found a QCI value of 6 for regular data use on a T-Mobile Connect plan on 5/14/2020.
I found a QCI value of 6 for regular data use on T-Mobile’s Magenta plan on 11/11/2020.
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)
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.
After running through my Premium Data, I found a QCI of 9 on 7/3/2020.
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.
I found a QCI of 9 for regular data use with Total Wireless on 6/2/2020.
Stetson Doggett found a QCI of 9 with Visible on 7/21/2020.
I found a QCI of 9 for regular data use on a second-generation Xfinity Mobile unlimited plan on 5/19/2020.
I found a QCI of 8 for regular data use on a third-generation by-the-gig plan on 7/3/2020.
Carriers using Sprint’s network (expanded)
Stetson Doggett found a QCI of 6 with Sprint Kickstart on 7/21/2020.
- 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.”
- When I say “regular data use,” I’m excluding voice calls, IMS signaling, and some atypical forms of data use.
- 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.
- Based on Table 6.1.7-A: Standardized QCI characteristics from 3GPP TS 23.203 V16.1.0.
- 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.
- I did this using a device that was compatible with Fi but not designated “Designed for Fi.”