Seeing Networks in Phoenix

Phoenix’s network infrastructure is both sprawling (from dense downtowns to the suburbs) and yet impressive (Phoenix is a prime location for datacenters, owing to its lack of natural disasters, proximity to the West Coast and Midwest, low land cost, and low nuclear-powered electricity cost. It’s also home to a number of corporate regional headquarters and call centers.)

What follows below is more or less findings of ongoing research. Readers are encouraged to get in touch if they would like to contribute other images and observations.

Manhole Covers

Manhole covers are one point of entry into the city's underground world, and their designs indicate what part of that world they connect to. Here are some manhole covers that might help you identify pieces of the Internet.


AT&T was the predecessor to Qwest, now Centurylink, which provides phone and DSL service to the entire metro area. These manholes are mostly owned by Centurylink now, although AT&T may still own backbone links across the country. PF.Net uses similar-looking manholes, and was renamed to Velocita which was a construction company that laid fiber-optic cable for other telecom companies until it was bought by AT&T in 2002. Generally long-distance or cross-town fiber optics, or local copper phone wires, will be buried beneath.

Qwest/Bell System

Predating CenturyLink and Qwest was U S WEST, Mountain Bell, Mountain States Telephone & Telegraph, and the original American Bell Telephone Company. "Ma Bell" consisted of the original AT&T and its subsidiaries, and was broken up into "incumbent local exchange carriers" due to the antitrust lawsuit over the telephone company monopoly in 1982. This allowed "competitive local exchange carriers" access to lease cables and facilities from the incumbents at a reasonable, regulated rate, and is why you are now able to switch phone or DSL companies much more easily than switching cable companies (if there even is a choice.) These manholes are probably functionally the same as the AT&T ones, and just carry a slightly different implication or history because of the different names that these carriers have taken over the years. No reason to replace a perfectly good manhole, right?

CATV (Coaxial Cable)

More like an underground pedestal or junction box than a manhole, these CATV boxes either provide access to building or campus coaxial cabling, or are just generically-labeled Cox Cable boxes. "CATV" means Cable TV, but coaxial cable networks can transmit data and closed-circuit video too.


This generic manhole is again often seen on campuses but might be provided by cities or carriers who provide common pathways for multiple forms of communication, or simply don't want to both putting their name on everything. Often the main reason for labeling these at all is to let city and construction crews know what's in the area to avoid surprises: there are many things underground which aren't properly labeled on city maps, so onsite labeling greatly helps workers.

Northwind (NRG Energy)

Downtown Phoenix has a chilled water network which uses energy at night to cool liquid, and pump it throughout downtown buildings during the day in lieu of typical air conditioning. Similar networks are installed at ASU's Tempe and Mesa campuses, as well as Tucson.

Street Markings

Sometimes you'll see a manhole cover that is surrounded with colorful markings. Whenever a contractor or construction company plans to do street excavation, utility companies will mark out the location of their underground cables so that the contractor knows to watch out for them.

There's a federal color-code standard for sidewalk markings. Sometimes the contractors follow it, sometimes they don't, but it's useful to know.

Orange refers to the broad catch-all of "Communications, alarm, signal lines, cables and conduit." This means that orange lines can be internet cables, television cables, telephone lines, or other kinds of conduits.

Red means electricity, yellow means gas, green means sewer, and blue means water.

The markings are sometimes really sloppy, and often in fragments. Sometimes you'll see several different labels in the same place.


Cox Communications is the local monopoly for Cable TV and High Speed Internet. They're only technically required to provide service to residential buildings, but lately have been improving their coaxial-cable installations at businesses. These markings generally indicate coaxial lines and can be found anywhere.


Cox also operates fiber optic loop backbones around most of the area. Fiber lines form the backbone for their cable service, and also make backbone connections to local datacenters and possibly even Cox markets in other cities and states. A traceroute command from a Cox-connected computer to an East Coast destination will often show that Cox lines are taken all the way to their headquarters in Atlanta, Georgia before hopping to another provider.


Level 3 is the main telecommunications backbone provider in the area, and as of 2016 is a subsidiary of CenturyLink. Depending on how exactly traffic gets routed, Level 3 is sometimes used in the Phoenix Area as a hop to get from the Cox to CenturyLink DSL networks, as well as for general transit to networks in other cities or owned by other providers Generally seen near datacenters. If you're thinking about how many things started out as AT&T, were split up by anti-monopoly rulings, and now are combining back into nearly the same giant conglomerates they were before, you're not alone. As an interesting aside, if you're interested in who owns national and international backbones, many companies publish this info in maps online. Just search for their name plus 'fiber map'.


These 'F' or 'FO' markings indicate any sort of Fiber Optic cables. Could be for local utilities, cities, transportation, private business, or well-known telecom providers. Construction workers are often more concerned about how to avoid breaking things under the road than they are who actually owns it. The parallel lines indicate how wide the line or trench is, and in this photo three are put together to indicate a bunch of cables lined up in a wide spacing.


MCI Communications was a telecom giant from the 1970s to 1990s, building more than 46,000 miles of fiber optics and offering a full suite of telecom services in many countries. It competed with AT&T, experienced trouble and was bought by WorldCom, and then most recently was bought by Verizon. They now do business under the Verizon name. As you can see, street and city-level designations often stay the same even after ownership and branding changes.


The City of Phoenix has a lot of telecommunications infrastructure -- whether for roads, internal networking, or other purposes. More prevalent downtown, their purpose can sometimes be guessed by seeing where they lead. You don't need to be a telecom company to lay stuff under the street... sometimes a permit and a backhoe is all it takes.


Related to the Northwind (NRG Energy) manholes above: it seems a fiber optic network runs alongside the chilled-water pipes to aid in communications and control over the water network.


Pedestals are structures usually on the roadside or side of buildings where cables can be rewired as the network grows or as customers disconnect their service: like visible, above-the-surface manholes.

Cable TV & Internet

Cox provides TV, Internet, and digital phone service to the entire metro area, primarily to residential areas but to some commercial areas as well. These pedestals are mostly just for passive junctions.

Phone & DSL (Neighborhood)

These neighborhood-sized pedestals can be powered, and they often connect city-wide fiber optic lines to hundreds of copper lines running to each side street and building.

Phone & DSL (Roadside)

These roadside pedestals can serve as junctions for 100 individual phone lines or more, and connect neighborhood or street lines to each building. In some older markets where cable has taken over, the cover can sometimes be seen falling off, or the patch panel hanging out of the pedestal, but normally they are locked with bolts that require a special tool to open.

Phone & DSL (Building-side)

These wall-mounted boxes demarcate phone-company-owned wires from building-owned wires and facilitate the connection between them. Usually the company-owned side is locked to prevent customer access.

Buried Fiber Optic Cable

Often spotted near the intersection of railroad tracks and streets, on side streets adjacent to major arterial roads, or along highways, these simply alert residents to the presence of fiber optic cables buried below. Backhoes are the sworn enemy of buried cable since they can slice through cables and even pipes without noticing, so "call before you dig" signage is very common around buried cable and pipe. Fiber is the preferred medium for communications that need to travel more than a few miles, and it's often easier to lay it alongside existing pathways than to dig up new paths or cross other things.

Light Rail

There are electrical and data cabinets at each light rail station to collect camera, digital signage, audio announcement, and track sensor wiring and transmit it to the operations control center located downtown across from the Van Buren and 1st Ave station. Along the route are 144 strands of fiber optic cable providing gigabit Ethernet, plus another 144 strands for traffic signals.

Highway Traffic Monitoring

The Arizona Department of Transportation operates sensors and cameras in and above the highway to monitor traffic conditions. The signals are collected and processed by equipment in these phonebooth-sized cabinets, and transmitted back to the control center via fiber optic cables. Not to be confused with similar-looking cabinets alongside railroad tracks.

Various Antennas

Wireless communication can be a great way to get information across town without digging or telephone poles, and can also make remote sensors cost effective via radio or cell-phone communication.

Traffic Sensors

Overhead sensors complement in-pavement sensors to detect cars for traffic management, wrong-way-driver detection, and automated signage activation.

Weather Stations

Used for everything from Salt River Project canal monitoring to airport operations, these stations monitor wind speed, direction, precipitation, humidity and more, solar-powered, and transmit its data over radio and the Internet. Many stations broadcast over the APRS network, which can be accessed via HAM radio and online.

Cellphone Towers

Identifiable by the multiple vertical panels usually arranged in a triangle or on the sides of buildings, each panel is a directional antenna which points into the center of a hexagonal cell. This arrangement provides good coverage of a highly-populated area without requiring a large antenna in the center of the area, which makes antenna placement easier. Often the builder of the tower uses the top tier and leases out the lower tiers to competitors, while either owning or leasing the land the tower is on.

Microwave Point-to-Point Antennas

Looking like large wedding cakes, speaker cones, or satellite dishes, the fabric or plastic covering prevents debris and moisture from getting into the metal antenna, which often just consists of the cylindrical metal sides and rear of the unit. Each antenna is directional and often pointed at a business's satellite office or a tall hill or building for relay purposes. Also used by television stations for live reporting from broadcast trucks which have their own dishes. Often seen at TV news stations, schools, hospitals, banks, and on hilltops.

Municipal WiFi

Seen mostly around college campuses, city buildings, and downtown areas, on streetlight poles. Also used for cameras. Some are remnants of the now-defunct WAZ Tempe network. The three antennas are needed to both provide coverage to the immediate area and connect to nearby antennas to form a mesh.


There are a few well-known locations that people tend to go to when they want to "see the internet" in Phoenix. Of course, there are plenty of not-so-famous buildings that store lots of data and connect networks to each other. Identifying these buildings when looking on the street is not always easy, but one telltale sign is to look for ventilation and cooling systems; computers generate a lot of heat. Alternatively, look for windows, or more accurately, the absence of them. Computers don't need to see! (Note: on much larger buildings, in particular skyscrapers, vents also could just be a sign of a mechanical floor, the centralized space dedicated to maintaining utility needs for the entire building.)

While this is by no means an exhaustive list, these are a few interesting starting points from which you can start looking.

17 East Virginia

Tucked away out of sight, but dressed up in blue. Level3 is practically synonymous with Internet Backbone in the Phoenix area. This location seems more like a carrier hotel than a datacenter.

120 East Van Buren

One of the most notable and iconic data centers and carrier hotels in the Downtown area. Formerly known as Phoenix Internet Gateway, it is now owned by Digital Realty. Nearby construction and infrastructure makes this a prime spot for network tourism.

811 South 16th Street

A bit larger than 17 E Virginia, this Level3 facility offers complete datacenter services, and is in a likely geographical location for making interstate connections.

1301 West University

This sprawling, windowless AT&T-branded complex advertises datacenter services but like 811 South 16th is positioned along major arterials and likely either serves a large area or connects directly to an interstate backbone.

3110 North Central

Seemingly located inside of a strip mall, this Zayo facility advertises connections to many carriers: CenturyLink, Cogent, Cox, Integra, Level3, Salt River Project, XO, and of course Zayo's own metro and long-haul network.

3220 North 3rd Street

Owned by TW Telecom until its purchase by Level3 in 2014, this unassuming building is probably mostly for phone and internet infrastructure. Formerly Time Warner Communications, they began in 1993 trying to sell hybrid fiber-coaxial telephone and internet to customers, but ended up mostly selling fiber access to other carriers.

3300 North Central

Another TW Telecom (now Level3) location, inside of an office building.

3930 East Watkins

XO Communications is a telecom company that often delivers service over other company lines. Their customers are mostly businesses. Like Phoenix NAP and 811 South 16th, the placement in an industrial area along major arterials means this location could have interstate fiber running up to its back door.

IO Phoenix

IO is a prominent operator of datacenters in the Phoenix area. Located at 615 North 48th Street, this location is its largest and was originally built as a water bottling plant. Large colorful water pipes arc through the main floor, providing redundant cooling to the chilling units. On cold days, large masses of steam can be seen rising from the radiators outside. This building is a landmark due to its iconic shape and visibility from the highway.

IO Scottsdale

The first IO location in the Phoenix area, this location is sometimes called "IO Princess" because it's located at 8521 East Princess Drive. Tucked behind an automatic gate next to a medical plaza, this location is a more traditional datacenter but still offers unique architecture.

Phoenix NAP

An aggressive new contender in the Phoenix datacenter scene, NAP (an abbreviation for Network Access Point) is known for its emphasis on physical security, with intimidating security guards, a futuristic man-trap, and a showy Network Operations Center with rows of TVs and technical staff. Every Phoenix datacenter nerd has a story about PHXNAP.