In a move designed to encourage the building of superfast broadband networks, the regulator said the new rules would also reduce the historical reliance on Openreach, BT’s infrastructure arm.
The new rules mean competitors must now have equal access to Openreach’s infrastructure, while the BT division must also repair and maintain the poles and clear blocked holes..
BT also has to ensure there is space on poles for rivals' cables and build a digital map so competitors can plan future networks.
Yih-Choung Teh, Ofcom's competition policy director, said: "We'll make it easier for companies to offer their own full-fibre broadband more cheaply by accessing Openreach's tunnels and telegraph poles.
"This will put other providers on a level playing field with BT, so they have the confidence to invest in their own full-fibre networks."
Regulator has tightened grip on Openreach
Ofcom has been steadily tightening its grip on Openreach’s activities after BT agreed last year to separate it from the rest of the business and put in place its own senior management structure.
Last month Ofcom proposed lower charges for the amount charged to rivals.
Currently Sky and TalkTalk pay £88.80 a year in wholesale charges for each individual superfast package, but Ofcom wants this reduced to £52.77 by 2020/21.
BT 'worst broadband' provider
Separately BT was rated close to bottom in a survey of UK broadband providers undertaken by consumer group Which? Only TalkTalk was rated lower by customers in a survey of 1,800 people.
BT accounts for a third of all broadband connections but was heavily criticised for price rises, connection outages, low connection speeds and poor customer service.
Shares in BT rose a shade to 312p.