BT confirmed last week that it would offer free Internet access for its BT Internet customers - but only at the weekend.
BT had earlier denied any such plans were in place.
Information on the new service was posted on the BT Internet site late last week and the company said that no further information would be made available.
From midnight on Friday until midnight Sunday from now on, customers will be able to access the Internet using an 0800 number. They will need to download new "dialler" software from the BT Internet Web site.
The offer is only available to existing Plan Unlimited Internet account holders, which costs £11.75 a month for unlimited server access, including free voice-over IP.
Even though Net usage during the free period is unlimited, customers will be logged out after two hours of usage or 20 minutes of inactivity.
The telecoms regulatory body, Oftel, dismissed charges that the scheme showed BT using its dominant position to attract customers with the offer of free calls.
"Our initial appraisal suggests it won't have any adverse effects on competition for the Internet access market due to the wide variety of services available," said an Oftel spokesman. "But we will closely monitor the situation and investigate any customer complaints."
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