CenturyLink proxies — AS209 residential DSL and fiber exits

CenturyLink is Lumen's residential brand

Lumen Technologies Inc. is the renamed CenturyLink — the company rebranded the corporate parent to Lumen in 2020 but kept CenturyLink as the consumer-facing brand for residential DSL and fiber service outside the Quantum Fiber-branded metros. For Proxaro purposes, "CenturyLink" and "Lumen residential" are the same thing.

AS209 is the backbone ASN — one of the oldest major US internet ASNs, registered in 1990 and historically carried Qwest / US West backbone traffic before the Lumen consolidation. The same ASN carries both the Tier-1 enterprise backbone and the residential exits. That's uncommon — most big US residential ISPs (Comcast, Charter, Cox) run dedicated consumer-facing ASNs separate from their business backbone.

The practical implication: AS209's peering graph is enormous. Lumen is a Tier-1 transit provider peering settlement-free with every other Tier-1; a residential CenturyLink exit on AS209 rides the same peering relationships as an enterprise customer paying for Lumen IP transit. The Tier-1 peering makes the hop count from a Lumen residential exit to almost any major cloud-hosted target minimal.

The residential CenturyLink footprint

CenturyLink's residential geography reflects Qwest / US West's old territory plus selected acquisitions:

• Colorado: CenturyLink's headquarter state (Denver) and densest residential fiber + DSL footprint. Quantum Fiber is deploying across Denver metro.
• Washington: Strong DSL + fiber presence in Seattle / Tacoma, and much of Eastern Washington.
• Arizona: Parts of Phoenix metro (competing with Cox) and DSL coverage statewide.
• Missouri: Legacy Sprint / US West territory in KC and STL.
• Utah, Wyoming, Idaho, Montana, Oregon: DSL presence across the Mountain West and Pacific Northwest rural.

CenturyLink is not a dense Northeast / Mid-Atlantic / Southeast carrier — Comcast, Spectrum, and AT&T Fiber dominate there. CenturyLink is the carrier for the Mountain West and Pacific Northwest.

Fingerprinting considerations

CenturyLink residential reads across most integrity stacks as "residential DSL" or "residential fiber" depending on the specific prefix. Trust signal is comparable to Comcast / Charter — an ordinary US home-broadband consumer. A few Lumen-specific wrinkles:

• Quantum Fiber-branded allocations read as "fiber" in some GeoIP databases and as "DSL" in others. Neither is wrong per se (the allocations come from the same AS209 pool) — integrity stacks that distinguish fiber from DSL may score them differently.
• AS209's Tier-1 backbone role means the same ASN carries very different traffic classes. Enterprise customers paying for Lumen IP transit also route through AS209. Detailed trust-graph lookups may tag the specific prefix as residential or business; commercial GeoIP defaults to the registered consumer tag.
• CenturyLink's CPE homogeneity is lower than Comcast's (more modem diversity, more rural DSL variations), which marginally diversifies the device-fingerprint signal.

When CenturyLink is the right pick

• Denver / Colorado residential work where CenturyLink is one of the two primary ISPs (alongside Comcast)
• Seattle residential when you want a non-Comcast fingerprint
• Phoenix fiber when you want an AS209 exit rather than Cox AS22773
• Any Mountain West or Pacific Northwest rural traffic where CenturyLink is the only carrier option

Pricing and pool access

CenturyLink AS209 ASN pinning is available on Carrier and above. Note the pool is smaller than Comcast or Spectrum — pool depth in non-Mountain-West markets is limited. Recommended starting state pools: Colorado, Washington, Arizona.

References

• Lumen 2024 Annual Report: residential subscriber count
• peeringdb.com — AS209 Lumen Technologies
• bgp.tools AS209 — Tier-1 peering and prefix inventory
• CAIDA AS Rank: AS209 customer cone (very large, reflecting Tier-1)