T-Mobile USA and Motorola have both responded to a request for information on Carrier IQ from Senator Al Franken, and both firms admitted to using the software on their handsets. Carrier IQ’s wide-reaching existence was revealed earlier this month by a security expert who pointed out that the software could be used by phone makers and carriers to spy on mobile phone users. T-Mobile said the software is installed on devices owned by an estimated 450,000 customers but that it uses the “technical data solely to understand what is happening on the device and the network so that [T-Mobile] can more effectively and directly troubleshoot issues.” T-Mobile also admitted Carrier IQ comes pre-loaded on the Galaxy S II, the HTC Amaze, the Samsung Exhibit II 4G, the BlackBerry Bold 9900, the BlackBerry Curve 9360, the BlackBerry Torch 9810 and LG’s MyTouch, MyTouch Q and LG DoublePlay. There’s no word yet of T-Mobile will follow in Sprint’s footprints and disable the software’s functionality. Motorola also said it installs Carrier IQ software on its Admiral, Titanium, Bravo and Atrix 2 phones, but only because Sprint and AT&T ask it to. “As of the end of the third-quarter of 2011, we have sold a total of approximately 145,000 units of these models to our wireless carrier partners,” said Motorola government relations senior vice president Dale Stone.