MVNO comparison
US Mobile QCI Levels Explained: Warp 5G vs Light Speed vs Dark Star
How Quality of Service Class Identifier (QCI) tiers map onto US Mobile’s Warp (Verizon), Light Speed (T‑Mobile), and Dark Star (AT&T) hosts—who gets priority data during congestion versus when slower speeds reflect policy caps or tower limits instead.
- Updated
- 2026-05-15
- Reading time
- 11 min
TL;DR
US Mobile’s three consumer networks do not share one priority ladder: Light Speed uses QCI 7 on every plan tier, while Warp and Dark Star put Unlimited Premium traffic on QCI 8 and Unlimited Starter on QCI 9—with additional policy rules that can throttle or shape usage separately from QoS congestion. Carrier implementation still matters: the same numbered QCI can feel different across hosts, so pick the network that wins in your zip code and read the unlimited FAQ copy alongside the QCI table.
- Per US Mobile’s public QCI explainer, Light Speed (T‑Mobile) assigns QCI 7 across all plan types on that network, while Warp (Verizon) and Dark Star (AT&T) use QCI 8 on Unlimited Premium and QCI 9 on Unlimited Starter.
- Congestion-time depriority (QoS/QCI scheduling) differs from billing-cycle “may slow after heavy usage” language that US Mobile publishes for some unlimited Starter combinations on Warp and Light Speed—not Dark Star Starter’s advertised high-speed framing. Always verify live plan pages before you switch.
- Lower QCI numbers are higher priority inside LTE nomenclature, but US Mobile explicitly warns that identical labels can behave differently depending on whether the host is Verizon, AT&T, or T‑Mobile—that is exactly why Warp vs Light Speed vs Dark Star is about host plus number, not the number alone.
- Field testing only isolates QoS sensitivity when RF, bands, handset, usage buckets, and time-of-day windows are aligned; fringe coverage dominates most “slow data” complaints.
QCI and 5QI in one paragraph
Quality of Service Class Identifier (QCI) is the LTE-era label that tells the scheduler how aggressively to service a data bearer when airtime is scarce. 5QI is the analogous concept in standalone 5G. Lower-numbered non-GBR classes (7 vs 8 vs 9) generally mean “move my packets before the other best-effort subscribers when the sector is maxed.” Nothing about QCI fixes weak signal, missing band support, or backhaul limits—capacity and coverage still come first.
For the broader MVNO frame (including why Reddit “speed test brags” often hide congestion), start with MVNO QCI levels and data deprioritization explained. For a lookup-style matrix across other carriers, pair this article with MVNO QCI levels master list.
How US Mobile maps QCI today (official)
The following table restates US Mobile’s own published mapping as of the 2025 QCI blog refresh—always cross-check US Mobile’s QCI explainer and plan pages before you port, because wholesale agreements evolve.
| US Mobile network (host) | Unlimited Premium | Unlimited Starter | Other notable SKUs |
|---|---|---|---|
| Light Speed (T‑Mobile) | QCI 7 (all plans on this network use the same published class) | QCI 7 | Same QCI 7 framing for every Light Speed SKU in US Mobile’s article |
| Warp (Verizon) | QCI 8 | QCI 9 | — |
| Dark Star (AT&T) | QCI 8 | QCI 9 | Flex / By‑the‑Gig defaults to QCI 9 with an optional QCI 8 add-on per US Mobile copy |
US Mobile also discusses Dark Star QCI 7 experiments (closed testing / VIP messaging in the same article). Treat any beta label as time-bound marketing, not something you can assume is on your consumer SIM today.
Why “QCI 7 on Light Speed” does not end the debate
US Mobile’s authors include a blunt retail warning: QCI 8 on Warp or Dark Star can outperform QCI 7 on Light Speed during busy hours because “the network matters as much as the number.” That is the same phenomenon this site emphasizes when comparing Verizon-style vs T‑mobile-style builds: spectral assets, site density, and how each host operationalizes QoS.
Practical takeaway: if you commute on T‑mobile n41 corridors, Light Speed’s higher QoS weighting plus great mid-band can feel incredible. If you roam rural Interstates dominated by Verizon macros, Warp may still win on coverage hours even when its published class is QCI 8 instead of QCI 7. Dark Star splits the difference on many suburban AT&T footprints.
Unlimited Premium vs Starter—priority and policy
Premium = published higher QoS tier (Warp / Dark Star)
For Verizon and AT&T hosts, Unlimited Premium is the Unlimited tier US Mobile associates with QCI 8—better congestion behavior than QCI 9 Starter when the sector is contested. Premium marketing also emphasizes unlimited priority data where US Mobile lists it; read the fine print on get-started unlimited for the exact clauses that apply to your cart.
Starter = published QCI 9 on Warp/Dark Star, but also read usage FAQs
Starter’s lower QoS floor matters in stadiums and rush-hour cells, yet many “my Starter line died after 70 GB” threads are actually policy-based management, not QCI. US Mobile’s unlimited onboarding copy has historically drawn a contrast: Warp and Light Speed Starter can reference slower speeds after large monthly usage (often illustrated around 70 GB), while Dark Star Unlimited Starter is described as keeping unlimited high-speed data on-device in the same help paths—subject to reasonable network management. Reconcile those sentences with your real usage; they change more often than the QCI explainer’s table.
Light Speed vs “Premium” naming
Because US Mobile’s QCI explainer assigns QCI 7 to every Light Speed plan, an Unlimited Premium line that you transfer onto Light Speed is still Unlimited Premium in the billing sense, but its air-interface priority class follows Light Speed’s published map—not the QCI 8 label that applies to Unlimited Premium on Warp or Dark Star. That is the clearest everyday example of retail tier name ≠ identical QoS across hosts; confirm the active network inside the US Mobile app whenever you compare speed tests.
When throttling occurs vs when “deprioritized” is just congestion
Use this diagnostic grid before you troubleshoot:
| Symptom pattern | Likely cause | What to verify |
|---|---|---|
| Slow only during commute or events, fine at 2 a.m. | Congestion-time deprioritization (QCI effect) | Repeat tests same cell ID; compare with a known priority line if ethical |
| Slow everywhere with bad RSRP/SINR | Coverage or device band gap | RF metrics, LTE vs NR SA mode, antenna issue |
| Slow after crossing a monthly usage threshold on Starter (Warp/Light Speed) | Policy-based slowdown | US Mobile unlimited FAQ + your data usage meter |
| Hotspot slows while phone data feels fine | Hotspot bucket / policy | Plan hotspot terms, not consumer QCI story |
Need a Verizon-reseller sanity check beyond US Mobile? See US Mobile Warp 5G review (priority data) and best Verizon MVNOs in 2026. For T‑mobile-flavored comparisons, open best T‑Mobile MVNOs in 2026. For AT&T-heavy households, bookmark best AT&T MVNOs in 2026.
Field-testing priority without pretending you work for the carrier
- Stabilize the experiment — Same handset model + firmware where possible; disable VPNs; note LTE anchor vs NR SA.
- Log RF + serving cell — RSRP/RSRQ/SINR snapshots beat single speed-test screenshots.
- Separate busy-hour from idle-hour runs — QoS tiers diverge only when the scheduler has contention.
- Track billing-cycle usage — So you do not confuse Starter policy shaping with congestion.
For dual-network comparisons involving Google Fi-style setups, see US Mobile vs Google Fi QCI deprioritization test—but treat any cross-brand numbers as illustrative, not perpetual guarantees.
Limitations
- Published QCI maps are consumer documentation, not contractual SLAs.
- Engineering menus sometimes surface 5QI or opaque bearer labels—helpful clues, not certified readings.
- Wholesale profiles can change silently; if performance shifts overnight, rerun tests before accusing your phone.
Disclaimer
Network Scrutiny publishes independent research guides. We cite US Mobile’s QCI article and plan disclosures for mapping claims; we do not have insider access to live provisioning databases. Confirm pricing, migration rules, hotspot limits, and reasonable-use policies on usmobile.com before you buy. Nothing here is legal or professional RF engineering advice.
FAQ
Short answers; details are in the article above.
- Not automatically. US Mobile’s own QCI article notes that QCI 7 is a higher priority class than QCI 8 or 9 on paper, but it also states that QCI 8 on Verizon or AT&T can still outperform QCI 7 on T‑Mobile during busy hours because the host network’s capacity and scheduling context matter as much as the QoS label. Treat QCI as a tie-breaker after coverage and spectral reality in your routines.
- On Warp and Dark Star, US Mobile publishes that Unlimited Premium includes QCI 8, while Unlimited Starter uses QCI 9. On Light Speed, its QCI article states that **every plan on that network**—including Unlimited Premium and Unlimited Starter—uses the same **QCI 7** mapping. Moving a line onto Light Speed via a [network transfer](https://www.usmobile.com/help/articles/946304) therefore adopts **Light Speed’s** published QoS profile, not Verizon’s or AT&T’s QCI 8/9 split, even if the marketing tier name still says “Premium.”
- Deprioritization is congestion-time scheduling: lower-priority QoS queues wait when the sector is saturated, then rebound when traffic clears. Throttling—or more accurately “managed speeds”—can follow published monthly usage thresholds on certain unlimited Starter combos (US Mobile cites ~70 GB framing for Warp and Light Speed Starter while describing Dark Star Unlimited Starter differently). QoS tier does not replace those FAQs; read them together with the QCI map.
- On Dark Star, US Mobile documents Flex / By‑the‑Gig lines as QCI 9 by default with an optional paid QCI 8 uplift on some bundles. Warp and Dark Star unlimited tiers use the Premium vs Starter split above. Pools inherit whatever plan SKU you attach—there is no universal “pool traffic is always QCI 8” rule without checking SKU + network pairing.