For its rated 10 Mbit you need at least 10 MHz spectral bandwidth to keep up, which worked fine even on Category 3 unshielded twisted pair (UTP) wiring, as is still commonly used for telephone wiring.

It adds 96 ISDN channels to standard 10 Mbps Ethernet and runs over the same Category 3 UTP that most 10Base-T networks use. Each ISDN B channel is 64 Kbps, providing a total bandwidth of 6.144 ...

With state-of-the-art DSP technology and mixed-mode signal technology, the RTL8153 offers high-speed transmission over CAT 5 UTP cable or CAT 3 UTP (10Mbps only) cable. Functions such as Crossover ...

With state-of-the-art DSP technology and mixed-mode signal technology, the RTL8153 offers high-speed transmission over CAT 5 UTP cable or CAT 3 UTP (10Mbps only) cable. Functions such as Crossover ...