The internet is not in the cloud. It runs on submarine cables, fibre backbones, radio towers, data centres, and satellites. This guide walks each layer, shows the scale of the global network, and explains what is under investment pressure. If you have ever wondered what the internet actually is physically, everything is here.
Every image, video, and message you send travels through physical infrastructure. Most of it is invisible: buried fibre, undersea cables, rooftop microwave links, and remote data centres. This physical layer is where the internet lives, and its scale, cost, and resilience are utility infrastructure questions. This guide covers the whole stack.
The layers of telecom infrastructure
| Layer | What it does | Scale |
|---|---|---|
| Submarine cables | Intercontinental fibre backbone | ~1.4 million km globally |
| Terrestrial fibre backbones | National and regional trunk lines | Millions of km |
| Last mile access | Copper, fibre, cable to premises | Billions of connections |
| Mobile radio access | Cell towers, small cells, macro sites | Millions of sites |
| Data centres | Compute, storage, hosting | ~10,000 large facilities |
| Satellites | Geo, MEO, LEO for backhaul and access | ~10,000 active satellites |
| Peering points and IXPs | Where networks exchange traffic | ~700 major exchanges |
Submarine cables
Over 95 percent of intercontinental data traffic runs on submarine cables. There are roughly 550 active cables globally, spanning about 1.4 million kilometres. Major routes cross the North Atlantic, Pacific, and around Africa; recent buildout has focused on Africa (2Africa cable) and India Middle East. Cables typically last 25 years and cost USD 100 to 500 million each. The Submarine Cable Map tracks every cable globally.
Terrestrial fibre backbones
Long haul fibre runs between cities on national and regional trunk lines. Modern fibre carries multiple wavelengths at 100 to 400 Gbps each, totalling terabits per fibre pair. Route diversity matters: dual redundant routes prevent single cable cuts from disconnecting cities. Investment is dominated by tier 1 backbone carriers, though hyperscale operators (Google, Microsoft, Meta) increasingly build private backbones.
The last mile problem
Getting fibre from the backbone to individual premises is the largest cost in most telecom deployments. The choices are:
| Technology | Speed range | Deployment context |
|---|---|---|
| Fibre to the home (FTTH) | Up to 10 Gbps | New builds; increasingly retrofit |
| Fibre to the node (FTTN) plus DSL | 50 to 500 Mbps | Legacy copper networks |
| Cable (DOCSIS) | Up to 10 Gbps | US, cable TV networks |
| Fixed wireless (5G, WISP) | 50 Mbps to 1 Gbps | Rural, dense urban |
| LEO satellite (Starlink) | 50 to 500 Mbps | Remote and rural |
Mobile radio access
Mobile networks consist of macro cell sites (large towers with hundreds of metres radius), small cells (street furniture in dense areas), and core network equipment. Global count is approximately 8 million cell sites. 5G rollout has densified networks in developed markets and is now scaling in emerging markets.
Data centres
Data centres host the compute and storage that back everything from cloud services to streaming video. Roughly 10,000 large facilities globally, ranging from single MW colos to gigawatt hyperscale campuses. Electricity consumption is around 1 to 2 percent of global electricity and rising as AI workloads scale. The IEA Electricity 2024 report tracks data centre electricity demand.
Satellites
Geostationary satellites (36,000 km altitude) provide broadcast TV, some enterprise VSAT, and government use. LEO constellations (Starlink, OneWeb, Kuiper) are much closer and provide broadband access with roughly 20 to 50 ms latency. Roughly 10,000 satellites are active in 2025, up from about 2,000 in 2020. The ITU coordinates spectrum and orbit allocation.
Internet exchange points and peering
Networks connect to each other at internet exchange points (IXPs). Amsterdam AMS IX, Frankfurt DE CIX, London LINX, and Singapore SGIX handle terabits per second of peering traffic. Increasingly, hyperscale operators bypass public IXPs with private direct peering. The peering ecosystem shapes the economics of the internet.
Power for telecoms
Climate resilience
Physical security
Submarine cables, data centres, and critical fibre routes are increasingly recognised as critical infrastructure. Cable cuts, whether accidental or deliberate, can disconnect entire regions. Security concerns have driven cable protection agreements between operators and geographic route diversity requirements.
Regulatory landscape
National telecom regulators oversee licensing, spectrum, competition, and universal service. The FCC in the US, Ofcom in the UK, ARCEP in France, and equivalents worldwide shape investment and access. The ITU coordinates internationally.
Investment picture
Global telecom capital investment runs roughly USD 300 to 400 billion per year, with fibre buildout, 5G densification, and data centre construction the largest categories. Digital divide funding programmes in the US (BEAD, USD 42 billion), EU, and elsewhere are accelerating rural and underserved deployment.
Where the industry is going
- Fibre to the home reaching majority coverage in developed markets by 2030.
- 5G standalone with network slicing enabling private industrial networks.
- LEO satellite broadband as complementary access in remote areas.
- AI workload driven data centre demand accelerating.
- Edge compute placing capacity closer to users for low latency applications.
Frequently asked questions
Where is the internet backbone?
Under the oceans and buried in national trunk lines. Submarine cables carry over 95 percent of intercontinental traffic.
Who owns submarine cables?
Consortiums of carriers historically. Hyperscale operators (Google, Meta) increasingly build their own or lead consortiums.
Is Starlink real internet?
Yes. LEO satellites provide genuine broadband access at 50 to 500 Mbps in most locations.
Why does 5G matter?
Higher speed and lower latency, plus network slicing for dedicated industrial and utility uses.
How much electricity do data centres use?
Roughly 1 to 2 percent of global electricity. AI demand may push this to 3 to 5 percent by 2030.
What is 6G?
The next mobile generation, targeted for around 2030. Will emphasise sensing, AI integration, and terahertz spectrum.
How resilient are these systems?
Route diversity provides good resilience against single points of failure. Coordinated attacks against multiple cable landings are the extreme scenario.
Are old copper networks dying?
Yes, gradually. Most developed markets are targeting full fibre transition by 2030 to 2035.
What is edge compute?
Computing capacity distributed closer to users, providing lower latency than central data centres for time sensitive applications.
How do I see telecom sites near me?
Country specific tower databases. In the US, FCC ULS. In the UK, Ofcom Sitefinder.
Summary
Telecom infrastructure is the physical layer of the internet: submarine cables, fibre backbones, cell towers, data centres, and satellites. It is a USD 300 billion per year investment sector supporting essentially every digital service. Understanding the layers helps make sense of contemporary debates about 5G, digital divide, satellite constellations, and AI driven data centre buildout. Every layer has its own economics, regulation, and resilience characteristics.
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