An effective digital strategy will "help get customers to be the advocate" for a banking business, one of Westpac's senior executive said on Friday.Scott Tanner, chief executive of Bank of Melbourne, told the FST Media banking technology conference in Melbourne that "customers who interact only through digital channels are renowned the world over for having narrower and shallower relationships with banks.""The key challenge with remote digital channels is how do we increase engagement?"Tanner said customers expected "consistency, and want a conversation opened in one channel to continue in another channel. They also expect consistent service in channel types.""If it starts online, we need to help them complete on [the] phone."Taking social media seriously is another opportunity, BOM has learned.Tanner said that at Bank of Melbourne we have "found those customers who interact with us via social media do 40 per cent more business than other customers."Tanner surveyed some highlights of customer use of digital channels at BOM, a platform that Westpac is using to renovate many of its business processes.He said 85 per cent of customers now transact using online and mobile. He expects this to rise to 95 per cent over the next five years.Tanner said there were 15.8 touch points per customer per month on average in 2012, of which 6.3 were online.The take up of tablet and mobile banking was occurring three times faster than the original take up of internet banking, he said.Seven per cent of sales were via digital channels, which Tanner expects to rise to 20 per cent in five years."For more complex needs, customers want face-to-face contact, so we'll continue to build branches or stores."Kelly Bayer Rosmarin, executive general manager at Commonwealth Bank, told the conference that 51 per cent of log-ins to internet banking were via mobile devices.She said there were 26 million log-ins made via mobile each month, while the bank had 1.56 million active mobile users.