Commonwealth Bank has confirmed that the three mobile platforms it intends to concentrate on are the iOS (for Apple's iPhones and iPads), the Android OS, and the Windows Mobile platform. CBA has effectively ruled out ever developing applications for the BlackBerry.Commonwealth Bank monitors access to its online services from mobile devices, and while the iPhone and Android are "going gangbusters", according to the general manager of online banking, Drew Unsworth, "I can't see us investing in BlackBerry", he said.  The bank has noted a tail-off in access to its systems from these phones.At a briefing held in Sydney yesterday, Andrew Murrell, general manager for channel banking, said there had been 2.7 million downloads of CBA mobile applications to date.Murrell said that within six to 18 months the bank expected mobiles to be the most popular channel for customers to use for interacting with their bank.  Demand for the Kaching iPhone app, which became available just before Christmas, remains strong, with the bank claiming there have been 120,000 downloads to date. It won't divulge how many of its iCarte cases it has sold, however. These are equipped with a Near Field Communication chip to facilitate contactless payments. The case - which is available for A$55 - was only ever intended as a stop-gap measure, however, as the bank expects future smartphones to be equipped with an NFC chip.CBA is unlikely to offer an NFC case for Android phones given the range of phone designs that exist.The Android version of Kaching is still under development, but Unsworth said it was likely to go to staff testing next month, prior to full release. CommSec, meanwhile, has recently launched an Android version of its latest app - although Android represented only about 15 per cent of the 30,000 downloads the app (which is also available for iPhones) experienced during its first 10 days on the market.Unsworth added that about 10 per cent of Kaching downloads today were being used on iPads. People who do use the app on their iPad simply see a larger version of the iPhone app. He said the bank was now trying to work out how it could make "more of an iPad app" that would harness more of the iPad's features.