Banks will rely less on their bank account numbers as the primary method of linking customers with those accounts, ANZ wrote, in its submission to the Senate banking inquiry.Echoing data used by the Australian Payments Clearing Association, ANZ noted that almost two thirds of non-cash retail payments rely on credit and debit card 15- and 16-digit numbers, as well as "other references developed by BPay and PayPal, rather than on account numbers."As the payments system evolves, it is likely that reliance on transaction account numbers as identifiers will reduce," ANZ wrote.ANZ was the most accommodating of the big banks in addressing the issue of portability of account numbers, something favoured by the consumer lobby and likely to be central to the imminent banking policy announcement from the Federal Government."In principle, we have no objection to portable account numbers," ANZ said."But, as with any form of regulation, the costs and benefits of implementing it need to be considered."ANZ quoted Choice data to argue that "the barriers to switching are not as significant as many commentators have suggested."Recent research by the consumer lobbyist found that 78.5 per cent of customers have not considered switching, ANZ said.Choice found that 7.6 per cent had switched.Another 11.8 per cent had considered switching but did not do so. Half of this group, or 5.9 per cent of the total, cited the level of effort as the major reason they had not switched. "This suggests that the number of people who want to switch banks and are discouraged by the effort is quite low," ANZ wrote.