BT app targets mobile calls

BT has launched a challenge to mobile phone operators, launching a smartphone service that allows phone calls over the internet.

SmartTalk, which the telecoms firm announced yesterday, allows BT customers to make calls which are then charged to their landline account, as if the calls were from a home phone.

But the launch of the service may concern mobile network operators such as Vodafone and O2, which are struggling with declining voice call revenues as more people communicate via social media.