Telstra cable broadband speeds are set to double for many customers across the country as the telco abandons its long-standing monthly fee to unlock maximum speeds.

Both Telstra and Optus throttle HFC cable broadband download speeds to 50 Mbps, unless customers pay an extra $20 or $30 per month respectively for a "Premium Speed Boost". This unlocks their cable's full potential of "up to 100 Mbps", in some cases reaching speeds of 120 Mbps.

Telstra customer value management executive Jana Kotatko says Telstra's move was driven in part by high demand for NBN connections in some areas, which is leading to delays. a