Moblie carriers Sprint and AT&T have revealed how much they each use data from Carrier IQ, the mobile data monitoring service that’s been raising eyebrows across the globe.

In the ongoing saga of Carrier IQ, we’ve focused a lot of attention on the company but relatively little on how carriers are using the information it gathers. The company collects information on around 150 million cell phones around the world — information about battery performance, app issues and dropped calls.

However, since a video was released that appeared to show the software logging keystrokes, many privacy advocates have become concerned about all the data Carrier IQ gathers, and exactly what wireless carriers are monitoring and using.

In detailed letters to Sen. Al Franken, who has taken a special interest in the Carrier IQ case and requested pertinent information from major carriers, both Sprint and AT&T talk about how they partnered with Carrier IQ. But the companies take very different approaches to working with Carrier IQ and its data.

“We appreciate Subcommittee Chairman Franken’s continued interest in protecting consumer privacy and look forward to our ongoing dialogue with the Senator to answer his additional questions,” said Andrew Coward, Carrier IQ’s vice president of marketing, in an email exchange with VentureBeat.

In its letter to Franken, Sprint says it uses Carrier IQ’s shortcode data diagnostically on around 26 million Sprint devices. It says, however, that the Carrier IQ software doesn’t gather data unless it’s asked to do so, and at any given time, only around 1.3 million of those devices might actually be gathering data.

In AT&T’s letter to Franken, the company says it has been working with Carrier IQ since March 2011. Currently, AT&T says around 900,000 of its devices have Carrier IQ deployed.

What both carriers did stress, however, was that they considered Carrier IQ’s diagnostic data to be critical to improving network speed and reliability, both things that customers are very passionate about. AT&T in particular says that when it logs location, it does so to improve cell coverage in that location.

Also, Sprint and AT&T noted that rather than spying on individual consumers, the companies creates “profiles” of types of mobile device behavior — after all, huge amounts of data like those gathered by Carrier IQ are most useful for businesses when aggregated and categorized to find patterns and trends.

In short, the carriers both claim to be using the kind of data Carrier IQ has previously stated it provides — shortcodes, not keystrokes — in a manner consistent with consumer expectations of security, customer service and privacy.

This hasn’t stopped consumers from taking preemptive action, though. A couple weeks ago, all major carriers as well as Carrier IQ were named in a class-action lawsuit, and the software provider went as far as requesting meetings with the FTC and FCC (and several senators) to answer questions and clear its name.

Stay tuned for more Carrier IQ news as the company’s moment in the spotlight continues to play out.