Some homes sit too far from town for cable, and the phone company never ran good copper down the road. The provider that reaches those homes often isn't running any wire at all. It's beaming the connection through the air from a tower on a hill to a small antenna bolted to the roof.
That provider is a Wireless ISP, or WISP, and it's one of the internet connection technologies CompTIA A+ Core 1 (220-1201) expects you to recognize under the Networking domain. The objective asks you to identify how a WISP delivers service, what conditions it needs to work, and how it compares to the wired and cellular options you'll also study. In exam terms, you need to know that a WISP is a fixed wireless technology that depends on line of sight, and you need to place it correctly against DSL, cable, fiber, satellite, and cellular when a scenario asks for the best fit.
This article stays focused on what a technician actually deals with: how the signal travels, what equipment sits at each end, why a tree can knock a customer offline, and how to reason through a service call. Picture a rural customer whose only realistic options are satellite or a WISP, and you'll have the mental model you need.
A WISP delivers internet over radio instead of over a wire
A Wireless ISP provides internet access using radio signals transmitted between fixed points. On one end is the provider's equipment, usually mounted on a tall structure like a tower, a grain silo, a water tank, or a tall building. On the other end is the customer's antenna, mounted on a roof or a pole and aimed back at the tower. The two exchange data over the air, and no cable runs between them.
The word "fixed" matters here. A WISP link connects two stationary locations. That's different from cellular data, where your phone moves and hands off between towers as you drive. A WISP antenna is aimed once during installation and stays pointed at the same tower. Because the endpoints don't move, the provider can use directional antennas that concentrate the signal into a narrow beam, which improves range and reduces interference.
WISPs exist mainly to solve a coverage problem. In rural and semi-rural areas, running fiber or coax to every home is expensive, so wired providers often skip them. A WISP can cover a wide area from a single elevated site, reaching customers that wired broadband ignored. That's the core reason the technology exists, and it's the context the exam usually wraps around it: the scenario describes a location with no cable and poor DSL, and asks what fits.
For a technician, the takeaway is that a WISP is broadband without the last-mile wire. Everything else about how it behaves, how fast it is, and how it fails comes from the fact that the connection travels through open air.
Line of sight is the single condition that makes or breaks the link
The most important thing to know about a WISP is that most deployments need a clear line of sight between the customer's antenna and the tower. Line of sight means the two antennas can effectively "see" each other with nothing solid blocking the path. Radio waves at the frequencies WISPs use travel in roughly straight lines and don't bend well around obstacles, so a hill, a building, or a stand of trees between the two points can weaken or kill the signal.
This is why WISP antennas end up on roofs, poles, and masts. Height clears obstructions. During a site survey, the installer is really asking one question: can I get a clean path from this roof to that tower? If a neighbor's tree line sits in the way, raising the antenna a few feet on a mast might clear it. If a ridge blocks the path entirely, that customer may simply be unreachable from that tower.
There's a subtlety the exam won't test but the field will. A clear visual path isn't quite enough. Radio signals travel through a football-shaped region around the straight line called the Fresnel zone, and objects that intrude into that zone degrade the signal even when the direct sightline looks clear. In practice this means an installer wants some margin above obstacles, not a beam that just barely grazes the treetops. You don't need the term for the exam, but understanding it explains why a link that "looks fine" can still perform poorly.
Trees are the classic real-world gotcha. A link installed in winter can degrade in spring when leaves fill in, and it can drop in a storm when wet foliage absorbs signal. Seasonal and weather-driven changes to line of sight are a common source of intermittent WISP complaints.
Some newer systems tolerate partial obstruction, described as near line of sight or non-line-of-sight, usually by using lower frequencies that penetrate obstacles better. Treat these as helpful exceptions, not the rule. For the exam, associate WISP with the line-of-sight requirement.
WISPs run on radio frequencies, mostly unlicensed bands
WISPs transmit on radio spectrum, and which band they use shapes range, speed, and how crowded the airwaves get. Most WISPs rely on unlicensed spectrum, the same public bands used by Wi-Fi, because no license fee or government coordination is required to operate there.
The common bands break down like this:
| Band | Type | General behavior |
|---|---|---|
| 2.4 GHz | Unlicensed | Longer range, better obstacle penetration, but crowded and slower |
| 5 GHz | Unlicensed | More capacity and speed, shorter range, needs clearer line of sight |
| 60 GHz | Unlicensed | Very high speed over short distances, easily blocked |
| Licensed bands | Licensed | Interference-protected, used for reliable backhaul and dense areas |
Lower frequencies like 2.4 GHz travel farther and push through minor obstructions more forgivingly, but the band is congested with Wi-Fi, cordless phones, and everything else, so speeds suffer. Higher frequencies like 5 GHz carry more data and are cleaner, but they demand a better line of sight and cover less distance. This trade-off between range and capacity runs through all wireless technology, and a WISP engineer picks a band to match the terrain and the customer density.
The unlicensed nature of these bands is a double-edged sword. It keeps costs down and lets small regional WISPs operate without buying spectrum, which is a big reason WISPs are often small local companies rather than national carriers. But unlicensed means shared, and shared means interference. Another WISP, a neighbor's Wi-Fi, or a new microwave link can appear on the same channel and degrade performance with no legal recourse. Larger or more serious WISPs sometimes pay for licensed spectrum precisely to avoid this, gaining protected airwaves at higher cost.
For the exam, you don't need to memorize channel plans.