Carphone Warehouse's TalkTalk service has been slammed by the Advertising Standards Authority (ASA) for misleading users over a promotion offering 'free calls'. 

Rival telecoms provider BT objected to a national press advert for TalkTalk that offered "free unlimited landline calls for three months" and that "TalkTalk customers talk Free Forever to each other". 

TalkTalk insisted that calls between its customers are free, and that users could make calls to other TalkTalk subscribers without paying for either line rental or calls. However, the ASA upheld BT's complaint and ruled against TalkTalk.

"The claim in the ad was about the benefits available to customers who took line rental," said the ASA. "We noted that all TalkTalk line rental customers automatically qualified for call plans."

The ASA found that two of TalkTalk's call plans involved a monthly charge, while a third was available at no extra charge.

Since all three plans offered free calls to other TalkTalk users, it ruled that those calls were an inclusive feature of the two plans which charged a monthly fee.

The ASA further ruled that TalkTalk should not describe those calls as free again, and advised the company to consult the Committee of Advertising Practice's Copy Advice team before advertising again.