What is a cell site? Masts, sectors, cells and bands explained

"Cell site", "cell tower", "mast" and "antenna" are often used as if they meant the same thing. They don't, and the difference explains why maps and registers count them differently.

The site, the mast and the antennas

• A cell site is a location where a carrier has installed radio equipment to serve mobile phones. It can be a dedicated lattice tower in a field, a slim pole by a motorway, a rooftop in a city, a water tower or a church steeple.
• The mast or support is the physical structure. Several carriers can install equipment on the same support.
• The antennas are the panels you see on the structure, usually rectangular and grey or white. Each one covers a slice of the area around the site.
• The equipment cabinet at the foot of the mast or on the roof holds the radio units and power supply.
• The backhaul connects the site to the carrier's network, by fibre or by a microwave dish pointing at another site.

Sectors and azimuths

Most sites split the area around them into sectors, typically three, each covering about 120 degrees. Each sector has its own antennas pointing in one direction, called the azimuth, measured in degrees clockwise from north (0° is north, 90° east, 180° south, 270° west).

On our map you can turn on sector directions to see where each antenna points. It is useful when aiming a router or an outdoor antenna: being in front of a sector gives a much better signal than being behind it.

Why one site carries dozens of "cells"

A cell is the radio coverage of one sector, on one frequency band, for one technology. A single site with three sectors, served by one carrier on 4G in four bands plus 5G in two bands, already has 18 cells. Add a second carrier and the number doubles.

This is why registers have far more records than masts. The French national register (ANFR) lists 760,569 live records for only 68,297 distinct support positions: each record is one carrier and one technology/band at one support. Our pages group records by mast, so a table row shows each mast once with all its carriers and generations.

How often carriers share a mast

Building a mast is expensive and often requires planning permission, so carriers frequently share. Tower companies own many sites and rent space to all four carriers, and in rural areas the carriers have agreements to share sites to extend coverage.

Among the 65,769 support positions used by at least one of the four main French networks:

Source: ANFR open data, live sites only, September 2026. Counted by Cell Site Map.

So about half of all supports are used by a single carrier. That is why the nearest mast to you may not serve your phone at all, and why each of our town pages lists the nearest mast per carrier.

Macro sites, small cells and indoor systems

• Macro sites are the classic tall masts and rooftops, covering from a few hundred metres in a dense city to several kilometres in the countryside, and more than 10 km on low bands over open land.
• Small cells are low-power units on street furniture or building fronts, used to add capacity in busy areas.
• Indoor systems (distributed antenna systems) serve stations, airports, shopping centres and tunnels.

Small, low-power equipment is not always in public registers. In France, the ANFR register covers installations above 5 watts.

A few terms you will see

• eNB / gNB: the 4G or 5G base station at a site. Its ID identifies the site; our eNB ID calculator extracts it from a cell ID.
• Band: the frequency range used, for example 800 MHz or 3.5 GHz. Our 5G by carrier guide shows which bands each French network uses.
• EARFCN / ARFCN: the channel number within a band, which our channel converter translates into a frequency.
• MIMO: using several antennas at once on the same channel to increase speed.