Telstra will begin switching off services delivered over its decades-old copper today, marking the first time it has relinquished control over telecommunications infrastructure to NBN Co.

The switch-off will be undertaken progressively in the first 15 areas to have received fibre, with exemptions for customers who have signed up for the NBN but are yet to receive it.

NBN Co was urging those who had failed to sign up to the NBN in those sites to do so by close of business yesterday or risk losing access to their copper-based landline and internet services and having to rely on mobile-based communications services.

At the start of the month, 750 premises of the 19,000 with active copper lines in the first test release sites were yet to request the NBN.

As part of an $11 billion deal, Telstra agreed to disconnect its copper network within 18 months of the NBN being delivered to an area to ensure NBN Co did not face competition from services delivered over the copper network.

The first 15 sites where copper will be progressively switched off are:

New South Wales - Armidale, Minnamurra and Kiama Downs

- Armidale, Minnamurra and Kiama Downs Victoria - South Morang and Brunswick

- South Morang and Brunswick Queensland - Townsville, Aitkenvale and Mundingburra

- Townsville, Aitkenvale and Mundingburra South Australia - Willunga

- Willunga Tasmania - Deloraine, George Town, Kingston Beach, Sorell, St Helens and Triabunna

Connecting to the NBN in those sites has not been smooth sailing for all. Kiama resident Andrew Seamons says it has been a frustrating experience.

"In 2013 we went down to readjust our internet plan to find that it was no longer available and that we were going to have to be forced onto the NBN. It's a move we didn't want to have to make," he told ABC Illawarra.

"We were quite happy with the service we were receiving, but due to the fact that it was going to be switched off, we had no choice. It's taken them nine to 10 months to actually change us over."

Measures to protect vulnerable customers

Telstra says it and other internet service providers will take steps to ensure vulnerable customers, such as those who have a copper-based medical alert service, are not left stranded by the switch-over.

"We will review communications sent to each customer to ensure they have been contacted a minimum number of times and are well informed about the changes," a Telstra spokeswoman said.

"A phased withdrawal of services will then commence starting with those customers who have already connected to the NBN or have confirmed to us that they do not wish to move to the NBN."

The construction of the NBN has been beset by delays, but telecommunications consultant Chris Coughlan says that is likely to benefit Telstra, at least initially.

"They will continue to earn better margins on existing ADSL and PSTN services than services provided via NBN Co," he said.

But Mr Coughlan says it could be a problem down the track.

"Telstra will start to become concerned when the number of services that can't be disconnected through some failure or delay of NBN Co impacts their ability to capitalise on the sale of assets, such as unneeded local exchanges," he said.

"Operationally, if the revenue from these few services does not meet the fixed costs of managing and maintaining the assets that facilitate them, then Telstra will also become concerned."