Banks have poured millions of dollars into their Web sites, Transversal said, but it may still be quicker for customers to pick up the phone to find out basic information.
Web sites of banks could provide answers for only half of routine questions asked online, with the majority offering just static FAQ pages.
Its survey of sites also noted that 30 percent of bank Web sites struggled to answer more than two out of 10 product or service questions.
Nearly a third of banks don't offer the option of e-mailing questions, it found. For those that did, the average reply time was 30 hours for a response. After the wait, only three out of 10 banks answered the question satisfactorily, so customers would then still need to phone the bank for more information.
By contrast, the company said, bank call-center response times have improved "dramatically," with 60 percent of calls answered within three minutes and the shortest wait times being just a few seconds.
U.K.-based Transversal said that customers are being pushed toward using the telephone, irrespective of their preferences, and that this reflects a failure by many banks to adopt a "cohesive online customer interaction strategy."
Steve Ranger of Silicon.com reported from London.