# The fixed-cost trap and the economics of the last mile
A carrier spends billions building a network before a single customer signs up. Once that network is live, the cost of adding one more subscriber is close to zero. That gap, between enormous upfront cost and near-zero marginal cost, is the single most important economic fact in telecom.
Understand it, and almost everything else about the industry (consolidation, price wars, coverage rules, the obsession with market sharemarket shareThe percentage of total industry sales your company captures in a given period. It measures competitive position relative to rivals in a defined market.Voir la définition complète →) suddenly makes sense.
Two kinds of cost matter here.
Fixed costs are the costs you pay regardless of how many customers you serve: cell towers, fiber-optic cable in the ground, spectrum licenses (the legal right to use radio frequencies, usually bought from the government), switching equipment, and network software.
Marginal cost is the cost of serving one additional customer once the network exists. In telecom, this is tiny. Adding a subscriber to a live mobile network costs the carrier almost nothing: a bit more data traffic, a SIM card, some billing overhead.
Compare this to a restaurant, where each extra meal needs more ingredients and labor. In telecom, the meal is basically free once the kitchen is built. The kitchen just costs a fortune.
The last mile is industry shorthand for the final connection between the core network and the customer's home or phone. It is the most expensive part of the network per user, because it does not scale the way the core does.
One fiber backbone can carry traffic for millions. But to reachreachThe number of unique people exposed to your message in a given period. Unlike impressions, reach counts each person once, no matter how often they see it.Voir la définition complète → ten thousand homes, you have to physically run cable (or build towers) past every single one of those ten thousand homes, whether or not they subscribe.
That is the trap. You pay to pass the home. You only earn if they sign up.
A useful term here is homes passed versus homes connected. A cable or fiber operator might pass a million homes with infrastructure but only connect 400,000 paying customers. The ratio of connected to passed is the penetration (or take rate), and it drives whether the build ever pays back.
If your costs are mostly fixed, then your profit per customer improves every time you add a customer, because you are spreading the same fixed cost over more people.
Picture a network that costs 1 billion per year to run, independent of customers.
The carrier with the most subscribers has the lowest cost per subscriber. That carrier can cut prices, outspend rivals on marketing, or invest more in the network, and still make money where a smaller rival cannot.
This is why telecom naturally tends toward a small number of large players. Scale is not a nice-to-have. It is the whole game.
This economics explains the constant wave of mergers in the sector. When two carriers combine, they can often run a single network instead of two, sharing towers and backbone. The fixed costs merge; the subscriber base adds up. Cost per subscriber drops immediately.
Regulators know this, which is why big telecom mergers get intense scrutiny. The efficiency gains are real, but so is the risk that going from four national carriers to three leaves customers with less choice and higher prices. The OECD's work on communications competition tracks how different countries balance this tension.
The recurring policy debate: how few carriers is too few? Three strong national networks or four weaker ones? There is no settled answer, and it varies by country.
Here is where economics collides with politics.
Left alone, a profit-seeking carrier builds only where the take rate justifies the last-mile cost: dense cities, wealthy suburbs, busy highways. Rural areas, where you pay to pass a farmhouse every few kilometers and maybe one household subscribes, never pay back.
So governments impose coverage obligations (also called universal service requirements): rules that force carriers to serve unprofitable areas as a condition of holding spectrum or operating licenses.
Common tools include:
The FCC's Universal Service Fund in the United States is a long-running example of this second approach.
The logic is simple. The market alone will not connect everyone, because the last-mile economics say no. Policy exists to override that "no" where society decides connectivity is essential.
The fixed-cost structure also explains why telecom price competition can turn vicious.
Because the marginal cost of one more customer is near zero, a carrier with spare network capacity can rationally accept almost any price above that near-zero marginal cost, at least in the short term. Winning a customer from a rival is almost pure gain.
This creates a temptation to keep cutting prices to grab share. Every rival faces the same math, so prices can spiral downward until they barely cover the fixed costs everyone is trying to spread.
That is why carriers fight so hard on churn (the rate at which customers leave). Losing a subscriber does not save you much cost (your fixed costs stay the same), but it removes a contribution to covering those fixed costs. In a high-fixed-cost business, keeping the customer you have is often cheaper than the near-zero marginal cost suggests, once you account for what it cost to acquire them.
There is no rest. Every technology generation (3G, 4G, 5G, and the early 5G-Advanced upgrades being deployed around 2026) demands a fresh wave of capexcapexCapital Expenditure (CapEx) is money spent to acquire, upgrade, or extend long-lived assets like equipment, property, or software that deliver value over multiple years.Voir la définition complète → (capital expenditurecapital expenditureCapital Expenditure (CapEx) is money spent to acquire, upgrade, or extend long-lived assets like equipment, property, or software that deliver value over multiple years.Voir la définition complète →, the spending on physical network assets).
Each upgrade resets the fixed-cost clock. Carriers spend billions again, then race to sign up enough subscribers to spread that new cost base before the next generation arrives. The scale advantage compounds: the biggest players can absorb each new capexcapexCapital Expenditure (CapEx) is money spent to acquire, upgrade, or extend long-lived assets like equipment, property, or software that deliver value over multiple years.Voir la définition complète → wave more easily.
Vérification des acquis
1. Why does the combination of enormous fixed costs and near-zero marginal cost explain telecom carriers' 'obsession with market share'?
2. A carrier compares itself to a restaurant to explain its cost structure. What is the key conceptual point of this analogy?
3. Why is the 'last mile' the most expensive part of the network on a per-user basis?
4. Select ALL correct answers about the distinction between 'homes passed' and 'homes connected'.
Sélectionnez toutes les réponses correctes.
5. Select ALL correct answers that are correctly classified as fixed costs in a telecom network.
Sélectionnez toutes les réponses correctes.
Imagine a town of 100,000 homes. A fiber operator spends to pass all of them.
Scenario A, high take rate (40 percent): 40,000 paying customers share the last-mile cost. Cost per customer is manageable, and the build pays back in a reasonable time.
Scenario B, low take rate (12 percent): only 12,000 customers share the exact same last-mile cost. Cost per customer is more than three times higher. The build may never pay back.
Notice what did not change: the network cost. What changed was penetration. This is why carriers obsess over take rate, why they bundle services (broadband plus mobile plus TV) to raise the value of each connection, and why they sometimes agree to network sharing deals: two rivals splitting the cost of towers or fiber while competing on retail plans and price.
Network sharing is the industry's direct response to the fixed-cost trap: share the unavoidable fixed cost, compete on everything else.
If you sell to carriers, remember that they are ruthlessly focused on either lowering fixed costs or raising subscribers per unit of infrastructure. A product that does one of those has a story. A product that does neither is a hard sell.
If you invest in or analyze carriers, penetration, churn, and cost per subscriber tell you more than headline revenue. A carrier growing subscribers on a fixed cost base is improving; one losing them is quietly getting worse even if revenue looks flat.
If you work in policy, every coverage rule is a decision to override last-mile economics, and someone (carriers, taxpayers, or urban subscribers cross-subsidizing rural ones) pays for it.