Everything You Need to Know About QCI (QoS Class Identifiers)

Ever noticed how your data speeds randomly slow down—even when you’re on an unlimited plan? Or why some people seem to get faster service in the same spot? That’s not just bad luck—it’s QCI (QoS Class Identifier) at work.

Your wireless provider uses QCI to decide who gets priority on the network, especially during peak hours. This affects everything from streaming, gaming, and video calls to how fast your apps load when the network is crowded. If you’ve ever wondered why some plans come with “premium data” while others get deprioritized, QCI is the reason.

In this guide, we’ll break down how QCI impacts your mobile experience, why it matters when choosing a plan, and what you can do to make sure you’re getting the best speeds possible. QCI significantly influences various outcomes, such as streaming quality and gaming performance. Let’s dive in!

What is QCI? (QoS Class Identifiers Explained)

Over the past twenty years, we’ve witnessed what many describe as the “rise of the digital age.” According to a Pew Research Study, 97% of Americans now own a cell phone, a massive jump from just 35% in 2011. With more people relying on their phones for everything—from streaming and social media to remote work and online classes—the demand for mobile bandwidth has skyrocketed.

To keep up, carriers like T-Mobile, Verizon, and AT&T use QoS Class Identifiers (QCI) to manage network traffic, ensuring high-priority users get the best experience, even during peak hours. Whether you’re gaming, on a video call, or streaming in HD, your QCI level plays a big role in determining your data speeds and overall network performance.

In simple terms, QCI is a mechanism used in LTE networks to assign priority levels to different types of data traffic. This system ensures that essential services like voice calls and emergency communications receive higher priority over less critical data, maintaining overall network efficiency.

Definition and Purpose of QCI

QCI, or Quality of Service Class Identifier, is a crucial mechanism in mobile networks designed to ensure that different types of data receive the appropriate quality of service. Essentially, QCI values act as a service class identifier, prioritizing traffic on LTE networks to manage network congestion effectively. This system is vital for maintaining the quality of critical services like voice calls and video calls, which require higher priority over less critical data traffic.

By allocating bandwidth based on QCI values, mobile networks can ensure that premium subscribers enjoy faster speeds and better service quality, even during peak usage times. This prioritization helps maintain a seamless user experience, especially for services that demand high reliability and low latency. In summary, QCI values play a pivotal role in managing data traffic, ensuring that essential services receive the bandwidth they need to function optimally.

Latency, Packet Delay Budget & Network Congestion: Why Your Data Slows at the Worst Times

Latency (aka lag) refers to the time it takes for data to travel from your phone to the internet and back. The risk of experiencing latency can be significant, but higher QCI levels can mitigate this risk by ensuring more consistent and faster data transmission. If you’re experiencing buffering while streaming or lag in online games, your QCI level might be the reason.

• Peak Hour Slowdowns: During high-traffic times (like evenings or at concerts, airports, and sports events), lower-QCI users experience slower speeds while premium plan users get priority.
• Throttling vs. Deprioritization: Some carriers throttle data after you reach a cap, while others just deprioritize you during congestion. If you’re on a plan with “premium data”, you’ll keep getting high-speed data even in busy areas.

Real-Life Examples: How QCI Impacts Streaming, Gaming & Hotspot Data

Streaming: If you’re binge-watching Netflix or TikTok and notice your video randomly drops to 480p, it’s likely due to a higher QCI level deprioritizing your data. The outcome of streaming quality is significantly affected by QCI levels, with higher QCI often resulting in lower resolution and buffering issues.

Gaming: Playing Call of Duty Mobile or Fortnite? Low-QCI users may experience lag spikes, making online gaming frustrating, while premium users get a smoother experience.

Hotspot Data: Many carriers limit hotspot speeds based on QCI levels. If you’re using your phone as a hotspot and notice slow speeds on other devices, it could be due to deprioritization.

How QCI Affects Your Mobile Experience

Not all data is treated equally. High-priority users (like those on premium plans) typically get faster speeds, while lower-tier users may experience deprioritization—aka slowdowns—when the network is busy.

• Higher QCI (Lower Priority, Slower Data): Budget plans, prepaid plans, and MVNOs (like Mint Mobile, Cricket Wireless, and Visible) often operate at a higher QCI level. That means they’re the first to slow down when traffic is high.
• Lower QCI (Higher Priority, Faster Data): Premium postpaid plans from T-Mobile, AT&T, and Verizon usually have a lower QCI, meaning they get the best data speeds even in congested areas.

If you’re on a prepaid plan or an MVNO, you might notice that your friend on a postpaid plan gets way better speeds in the same location. That’s QCI working behind the scenes, ensuring that not all users receive the same level of prioritization.

How Major Carriers Utilize QCI

We know all about the “big three” which are the three major networks in the country: Verizon, AT&T, and T-Mobile. These companies each have their own Observed QCI Values by many different sources online, from Reddit users and other tech blogs alike. Taking action based on QCI data is crucial for optimizing network performance and making informed decisions.

QCI values 6 through 9 are reserved for data plans. QCI value 9 is considered to be “deprioritized” while 6, 7, and 8 are considered to be “premium.”

Specific thank you to Reddit user Ethrem and the FixVerizon blog for some of these data points.

Verizon

Verizon only uses QCI levels 8 and 9 for consumer plans, unless you are a Verizon Frontline member- which means you’re getting either fast or slow service with no in-betweens. 

Plans under QCI level 8: Most Postpaid plans fall under this category (except for 5G Start and Welcome Unlimited). Play More Unlimited, Do More Unlimited, and Get More Unlimited. As well as their Xfinity Mobile: By The Gig plan, Unlimited Plus plan, and Unlimited Premium plan.

Plans under QCI level 9: 5G Start, Welcome Unlimited, and all other prepaid mobile plans fall under this value besides the Unlimited Plus plan including prepaid MVNOs. 

AT&T

AT&T also mainly uses QCI levels 8 and 9. However their Unlimited Elite plan falls under QCI level 7.

Plans under QCI level 8: Most phone plans under AT&T are under QCI level 8 including Unlimited Extra, Prepaid Unlimited Plus and Prepaid Unlimited MAX. MVNO plans like Cricket More and PureTalk are also under 8.

Plans under QCI level 9: Unlimited Prepaid and Unlimited Starter Postpaid plans, along with Red Pocket Mobile and Boost Mobile. You’ll find that most of AT&T’s MVNOs are QCI level 9.

T-Mobile

T-Mobile uses QCI levels 6, 7, 8, and 9 for consumer plans. 

Plans under QCI level 6: Almost all plans under T-Mobile are under QCI level 6 which means your data is being prioritized above Verizon and AT&T plans at a higher rate. Magenta Postpaid plans and their Connect by T-Mobile Prepaid plan is under level 6. Along with their MVNO Google Fi plans.

Plans under QCI level 7: T-Mobile’s Essentials plan is under level 7. MVNOs like Mint Mobile, Tello and Metro by T-Mobile also fall under this category.

Plans under QCI level 8: No phone plans fall under this category, it is used for Home Internet Products.

Plans under QCI level 9: Home Internet users will experience a drop in level after they’ve exceeded their 1.2TB usage of the month, as well as phone data and hotspot usage. 

Acronyms to Understand: QCI, LTE, GBR, & More

This is where we get into the more technical part of the article, so get out your notepad and follow along as we cover some acronyms to know when you’re researching QCI.

QCI: QCI stands for Quality of Service Class Identifier or Quality Class Identifier. It’s the framework used for your LTE and 5G services to mark and prioritize the different kinds of traffic used on the internet: video calling, voice calling, playing games, etc. It’s what secure’s that the traffic and services are allocated to the right level of prioritization. 

LTE: Some Smartphone users will see a little “LTE” or 5G” at the top of their phone screens. LTE stands for Long-Term Evolution which is the fourth generation (4G) successor of 3G. It provides wireless broadband connection for mobile devices everywhere. 

GBR: GBR stands for Guaranteed Bit Rate. It’s a common term used when describing the amount of data that can be transferred over a network at a guaranteed rate. GBR is good to know when you’re doing something like playing the latest triple A video game so you can ensure a buttery-smooth gaming experience. And in times of network congestion you’d still be “guaranteed” a certain level of bit rate even at those peak times.

PD: PD stands for Packet Delay. It’s the time it takes for a “packet” of data to go from its source to its intended destination. It is measured in ms (milliseconds). This measures the reliability of a strong network connection, think about when you’re sending an email, if it sends and delivers super fast- that’s a good measure of packet delay. While Packet Error Loss Rate is “the number of sent packets minus the number of received packets in a portion of time,” according to Science Direct. (Aka that’s where math gets involved). 

IMS: IMS stands for IP Multimedia Core Network Subsystem. It’s the system used for delivering multimedia communications like video calls, voice calls, and text messages. It’s what makes calling and texting our friends, family members, and businesses possible.

QCI Levels and Their Differences

There are nine QCI values on the 5G and LTE networks, but only eight are possible- (nine are being saved for future uses). Each value represents a priority designated by a QoS class.

Monitoring risk factors associated with different QCI levels is crucial for improving healthcare outcomes and managing costs effectively.

QCI values are based on a few requirements:

• Latency
• Packet Loss (Packet Delay Budget and Packet Error Loss Rate)
• Reliability

The table, which represents LTE QCI, below is thanks to Wireless Telecom on Youtube:

Now let’s breakdown QCI values used in both LTE and 5G networks:

Now it’s good to note that not all networks will follow this exact estimate of QCI values. It may depend on the network’s policies and own priorities. 

QCI in 5G and Future Networks

As mobile networks evolve, so does the concept of QCI. In 5G networks, QCI is transforming into 5QI (5G QoS Identifier), introducing even more granularity in priority levels and specialized services. 5QI is designed to handle the higher speeds, lower latency, and broader use cases that 5G networks offer, making it a crucial component for future mobile services.

5QI values are used to manage network traffic and ensure quality of service in 5G networks, supporting advanced applications like connected vehicles and IoT devices. This evolution allows for more precise prioritization and allocation of bandwidth, ensuring that critical services receive the necessary resources to function optimally. As we move into the future, 5QI will play a pivotal role in maintaining the quality and reliability of services in increasingly complex and high-demand network environments.

How to Check Your QCI and Network Priority

Carriers don’t advertise QCI levels, but you can still check them using these methods:

For Android Users

• Network Signal Guru: This app (for rooted devices) gives you detailed network info, including QCI values, LTE bands, and deprioritization status.
• NetMonster: Another solid option for checking cell tower priority and network data, but QCI readings may be limited based on your device.

For iPhone Users

• Field Test Mode: Dial 3001#12345# and press call. This opens a hidden menu with detailed signal strength and network stats, though it doesn’t display QCI directly.

If these tools don’t work, your best bet is to test your data speeds in different locations and compare performance with someone on a higher-priority plan.

Final Thoughts

When choosing a wireless provider or switching to a new cell phone plan, comparing QCI levels can help you avoid slow speeds and frustrating lag. Higher-priority plans (lower QCI numbers) mean better performance, while lower-priority plans (higher QCI numbers) are more likely to experience deprioritization when the network gets busy.

Understanding QCI isn’t just for tech nerds—it’s for anyone who relies on their phone for streaming, gaming, work, or staying connected. The more you know about network priority, the better choices you can make to get the fastest, most reliable data speeds. If you want a smooth mobile experience, choosing the right plan with the right QCI level is the way to go. Taking action based on QCI data ensures you select the best plan to meet your needs.