Colocation Facilities and Carrier Hotels

Despite the move to IP-based communications, voice networks still depend on physical infrastructure. Carriers must physically connect their networks to exchange traffic, and those connections happen at colocation facilities — data centers where multiple carriers converge to interconnect. The most important of these are known as carrier hotels.

What Is a Carrier Hotel?

A carrier hotel is a colocation facility where a large number of telecommunications carriers maintain equipment and interconnect with each other. These buildings are the physical crossroads of the telecom network — the places where fiber from different carriers comes together in the same building, enabling direct peering without building dedicated links between every pair of carriers.

The defining feature is the meet-me room: a shared space within the facility where carriers can establish cross-connects (physical cables) between their equipment. A carrier with a presence in the meet-me room can interconnect with any other carrier in the same building by ordering a cross-connect — typically a fiber patch cable running a few hundred feet.

Notable Carrier Hotels

Several buildings have become legendary in the telecom industry due to the concentration of carriers and network infrastructure they house:

60 Hudson Street, New York

Originally the Western Union building, 60 Hudson is one of the most interconnected buildings in the world. Hundreds of carriers, ISPs, and content providers have a presence here. It serves as a major peering point for the northeastern United States.

111 Eighth Avenue, New York

A massive 2.9-million-square-foot facility (owned by Google) that houses numerous carrier PoPs and serves as a key interconnection hub for New York metro.

One Wilshire, Los Angeles

The premier carrier hotel on the US West Coast. One Wilshire is the primary interconnection point between transpacific submarine cables and the US domestic network, making it critical for US-Asia traffic.

350 East Cermak, Chicago

The largest data center in Chicago and a major interconnection point for the Midwest. Critical for carriers serving the Chicago area codes and for east-west cross-country transit.

Westin Building Exchange, Seattle

The primary interconnection hub for the Pacific Northwest, housing over 200 networks.

Why Physical Interconnection Matters

In the IP era, it might seem like physical proximity is irrelevant — packets can travel across the internet between any two points. But for carrier-grade voice, physical interconnection still matters:

Latency

Cross-connects within a carrier hotel add less than 1 millisecond of latency. Traversing the public internet between two carriers might add 20-100+ milliseconds. For real-time voice, every millisecond matters.

Reliability

A direct fiber cross-connect is more reliable than a path through the public internet. Carrier-grade voice requires five-nines (99.999%) availability. Direct interconnection within a controlled environment helps achieve that.

Cost

Direct peering via a cross-connect eliminates transit fees. Two carriers exchanging millions of minutes per month save significantly by peering directly rather than paying a transit carrier.

Quality Control

Direct interconnection gives both carriers visibility into the handoff point. They can monitor the cross-connect for errors, packet loss, and degradation. Traffic sent through the public internet or via transit is harder to troubleshoot.

Interconnection Within Carrier Hotels

The typical interconnection setup:

1. Both carriers lease space in the same carrier hotel (cage, cabinet, or suite)
2. Both carriers bring fiber to the building (from their network to the facility)
3. Cross-connect ordered: A physical fiber connection is run through the meet-me room between the two carriers’ spaces
4. Routing configured: Each carrier configures their SBCs or switches to send and receive voice traffic over the cross-connect
5. Traffic flows: Calls between the two carriers’ networks traverse this direct path

For IP-based interconnection, the cross-connect typically carries Ethernet (1G, 10G, or 100G). For legacy TDM, it might carry DS3 or SONET circuits.

Carrier Hotels and NPA/NXX Routing

The geographic distribution of carrier hotels affects voice routing patterns:

• Carriers with PoPs in major carrier hotels can offer direct-peered routes to more destinations, resulting in better quality and lower latency
• NPA/NXX data reflects which carriers have infrastructure in which regions — a carrier’s NXX holdings correlate with their physical presence
• LATA boundaries roughly correspond to metro areas, and major carrier hotels tend to be located in LATA hub cities

Further Reading

• Trunking and Carrier Interconnection — the logical layer of carrier interconnection
• The PSTN Explained — the network infrastructure connecting these facilities
• VoIP Network Architecture — modern network design using these interconnection points