FTTH, or fiber to the home, is a fixed broadband access architecture in which optical fiber runs all the way from the operator’s central office into each individual dwelling, ending at an optical network terminal inside the home. In telecommunications, FTTH is regarded as the most future-proof form of last-mile access, because the fiber itself can carry far more capacity than any current service uses.
FTTH differs from hybrid approaches such as FTTC (fiber to the cabinet) or cable networks, where the final section still uses copper. With FTTH, no copper remains in the access path, so speed no longer falls with distance and upgrades are achieved mainly by replacing the electronics at both ends rather than the cable in the ground.
How an FTTH network is built
An FTTH network runs from an optical line terminal (OLT) in the operator’s central office through feeder cables, distribution points and drop cables to the optical network terminal (ONT) in the customer premises. Most deployments are passive optical networks (PON), in which unpowered optical splitters divide one fiber among many homes.
| Component | Location | Function |
|---|---|---|
| OLT | Central office or exchange | Transmits and receives traffic for many PON ports |
| Feeder fiber | Between exchange and street cabinet | Carries aggregated traffic |
| Optical splitter | Cabinet or distribution point | Divides one fiber into 8 to 64 or more paths |
| Drop cable | From street to building | Connects the individual home |
| ONT | Inside the home | Converts optical signals to Ethernet |
The alternative to PON is a point-to-point (P2P) architecture, in which each home has its own dedicated fiber back to the central office. P2P uses more fiber and switch ports but gives each subscriber an unshared connection and simplifies unbundling for competing operators.
PON standards used in FTTH
Most FTTH lines run on standardized PON technologies from the ITU-T or the IEEE. In a PON, the capacity of one port is shared by all homes behind the splitter, using time division in the upstream direction, so the split ratio and the number of active users determine how much each home can sustain at peak times.
| Standard | Downstream capacity | Upstream capacity | Status |
|---|---|---|---|
| GPON | About 2.5 Gbps | About 1.25 Gbps | Widely deployed base |
| XG-PON | About 10 Gbps | About 2.5 Gbps | Transitional upgrade |
| XGS-PON | About 10 Gbps | About 10 Gbps | Current mainstream for new builds |
| 25GS-PON | About 25 Gbps | About 10-25 Gbps | Early deployments |
| 50G-PON | About 50 Gbps | Up to about 50 Gbps | Emerging next generation |
| EPON and 10G-EPON | 1 or 10 Gbps | 1 or 10 Gbps | IEEE family, common in parts of Asia |
Because newer PON generations use different wavelengths, they can coexist on the same fiber. An operator can add an XGS-PON card at the OLT and swap a customer’s ONT while neighbors stay on GPON, which makes upgrades gradual and inexpensive compared with the original civil works.
FTTH compared with other broadband access
The family of fiber architectures is often written as FTTx, where the letter shows how close the fiber reaches to the user. The closer it reaches, the shorter the remaining copper or coaxial section and the higher and more stable the achievable speed.
| Technology | Last segment | Typical maximum offered speed | Distance sensitivity |
|---|---|---|---|
| FTTH | Fiber into the home | 1-10 Gbps, symmetric possible | Very low over many kilometers |
| FTTB (fiber to the building) | Copper or Ethernet inside the building | Hundreds of Mbps to 1 Gbps | Low |
| FTTC with VDSL2 | Copper pair from street cabinet | Tens to a few hundred Mbps | High, drops with line length |
| Cable (DOCSIS 3.1) | Shared coaxial cable | Around 1 Gbps down, less up | Moderate, shared segment |
| FWA | Radio link from a mobile site | Tens to hundreds of Mbps | Depends on signal and load |
Beyond speed, FTTH typically delivers low and stable latency, symmetric upload capacity and lower energy use per subscriber than copper networks, because a passive network needs no powered equipment in the street.
Deployment costs and practical choices
The dominant cost of FTTH is civil works: trenching, ducts, poles and building wiring, often the largest share of the total investment. Operators reduce cost by reusing existing ducts and poles, using micro-trenching, and choosing aerial cables where permitted.
| Decision | Options | Effect |
|---|---|---|
| Architecture | PON or point-to-point | Fiber count, sharing and open access |
| Split ratio | 1:32 or 1:64 typical | Capacity per home and reach |
| Cable route | Underground or aerial | Cost, speed of build, resilience |
| Business model | Vertically integrated or wholesale open access | Retail competition, take-up |
A frequent distinction is between homes passed and homes connected. Fiber can run past a building for years before a household orders service, and the final drop and in-home installation are often the slowest and most labor-intensive step.
Limitations and common misconceptions
- FTTH speed is still a plan, not the fiber limit. The service tier and ONT determine the speed, not the glass itself.
- Wi-Fi is often the real bottleneck. A gigabit fiber line may deliver far less to a laptop over an older or poorly placed router.
- Fiber does not carry power. During a power cut, the ONT and router stop unless they have backup power, which matters for emergency calls.
- Fiber to the building is not FTTH. Marketing may label FTTB or even FTTC as fiber broadband, although copper still carries the last section.
- Fiber is not fragile in service, but bending a drop cable too sharply during installation can raise loss and cause faults.
Put simply
FTTH means that a glass fiber cable runs right into the home, instead of old copper telephone wire or a television cable doing the last stretch. Data travels through the fiber as pulses of light.
Because light in glass hardly weakens over distance, the connection stays fast and steady whether a home is next to the exchange or several kilometers away. When faster speeds are needed later, the operator usually only changes the boxes at each end, not the cable.
In practice
A small town of about 4,000 households replaces its aging copper network with GPON-based FTTH, using a 1:32 split and reusing existing telephone ducts for most streets. Civil works take eighteen months, and within two years about half of the homes passed have ordered service.
A family running a home architecture office moves from VDSL at 50 Mbps down and 10 Mbps up to a 1 Gbps symmetric fiber plan. Uploading large drawing files to clients drops from tens of minutes to under a minute. Five years later, the operator adds XGS-PON cards at the OLT and replaces only the family’s ONT to offer multi-gigabit tiers, without digging up a single street.