Network and infrastructure
FTTH fibre
Acronym: FTTH
FTTH, or fibre to the home, runs optical fibre all the way into the subscriber's home or premises, replacing the copper pair.
Light replaces electric current along the whole local loop, removing the attenuation that limited copper speeds over distance. The drawback is structural: a fibre carries only digital data and powers nothing. A landline only exists on it as voice over IP, provided by the router or a box supplied by the operator.
Why it matters for fax
On an FTTH line, the router's phone socket is not a line: it is an adapter that turns the signal into packets. A fax machine plugged into it sometimes works, often fails after the first page, and depends entirely on how the operator handles fax over IP.