Banks were yesterday warned to gird their loins for further assaults on their turf from technology led by the likes of PayPal, Visa, Google and Apple which all wanted to own variants of the e-wallet.Mark Zawacki, founder and managing partner of Milestone Group, a new economy strategy consultant based in Silicon Valley, said that with more mobile phones than toothbrushes (reputedly) now being sold each year, the mobile platform was ubiquitous and increasingly being seen as a payments platform.Zawacki was speaking at Amplify, the biennial ideas festival run by AMP, and said that the advent of near field communication technologies were enabling mobile payments and that technology companies were starting to "create walls around their systems to keep you sticky there."Speakers at Amplify also pointed to other developments challenging the banks such as the free Square app available in the US for Android devices, iPhones and iPads which allows merchants to accept credit card payments without having to sign up to a bank's system. Square charges a 2.75 per cent fee for every swipe and represented a "huge threat to banks" according to Oliver Weidlich, a director at Mobile Experience, which designed Westpac's iPhone app.Meanwhile telecommunications companies, were also in a position to establish themselves as banks according to Ray Wang, CEO of Constellation Research Group, as they were already at the centre of any financial transactions conducted using mobile phones. Bob Egan, CEO of the Sepharim Group, agreed that NFC represented a challenge to traditional cash or banking transactions. He said that coupled with smart applications that collected location data from phones and mashed that up with individual buying histories it would be possible to develop applications that allowed mobile phones to be used both as e-wallets and as conduits for individually tailored marketing campaigns.He envisaged retail applications making use of "big data" such that a cereal maker could be advised when an individual who regularly bought their breakfast cereal, but not their muesli bars, was in a supermarket, and then be able to send a tailored coupon to the mobile phone offering them a free muesli bar from the checkout.