In response to a request for more information from Senator Al Franken, AT&T, Sprint, Samsung, HTC, and Carrier IQ have responded with letters detailing their use of Carrier IQ's software on their handsets. Sprint is by far the biggest user of the software, admitting to installations on 26 million devices. Additionally, HTC has, for the first time, directly and publicly addressed the fact that Carrier IQ blames it for the insecure log files found on its devices — though not in a way that's likely to satisfy unhappy users. Another surprise: AT&T's network and dropped calls reporting app, Mark the Spot, utilizes Carrier IQ (though not on the iPhone).

All told, it's safe to estimate that Carrier IQ's software is installed on over 30 million US devices and now, for the first time, the companies involved are publicly naming them. We break it all down for you below.

AT&T

AT&T says that its usage of Carrier IQ's software is limited strictly to "collect diagnostic information about its network." AT&T also lists all of the handsets it sells that have Carrier IQ's software installed: the Pantech Pursuit II, Pantech Breeze 3, Pantech P5000, Pantech Pocket, Sierra Wireless Shockwave, LG Thrill, ZTE Avail, ZTE Z331, Xperia Play, Motorola Atrix 2, and the Motorola Bravo. The software is present on the HTC Vivid, LG Nitro, and Samsung Skyrocket as well, but on those three devices the network says Carrier IQ's software "has not been activated due to the potential for the software agent to interfere with the performance of those devices."

Another new revelation is that AT&T is using Carrier IQ in its own branded software called Mark the Spot, an app designed to allow smartphone users to "provide feedback on network user experience to AT&T." In other words, it's the software that many BlackBerry and Android users have been installing and using to help tell AT&T about problems. If you're not fond of Carrier IQ, it's probably a good idea to uninstall it. As for iPhone users, AT&T says that it has never used Carrier IQ in the iOS version of the software.

In total, AT&T reports that it has 575,000 devices actively sending the carrier data using Carrier IQ's software, out of an install-base of 900,000 devices. The carrier says that accounts for about one percent of its total market.

Sprint

Sprint reports that Carrier IQ software is installed on a whopping 26 million devices on its network. However, Sprint also says that at any given time not all of those devices are actively sending data, instead they only report when Sprint's network "tasks" the handset to send in information. At any given time, Sprint says, 1.3 million devices may be actively doing that. Sprint also says that it only uses Carrier IQ software for network diagnostics, which it has been doing since 2006.

Sprint also admitted that it receives the URLs of the websites users visit from Carrier IQ, but notes that it already knew that anyway "from routing the request on its network." Carrier IQ's reporting of the URL, Sprint says, is simply there to help "troubleshoot loading latencies or other errors."

Sprint declined to list every single handset that has Carrier IQ software installed, but did list Audiovox, Franklin, HTC, Huawei, Kyocera, LG, Motorola, Novatel, Palmone, Samsung, Sanyo, and Sierra Wireless as manufacturers whose handsets may include the software on Sprint's network.

Samsung

Samsung naturally pointed out that Carrier IQ is there for the carriers, not Samsung, and so Samsung installs the software at their behest. Samsung lists a raft of phones, 28 in all, that use Carrier IQ's software on Sprint. Two phones on T-Mobile, four on Cricket, and one on AT&T. Samsung specifically mentions the Galaxy S II Skyrocket, Galaxy S II Epic 4G Touch, Epic 4G, Galaxy Tab 3G for Sprint, Transform Ultra, Conquer 4G, Replenish, Galaxy Prevail on Boost Mobile, Transform, Intercept, Moment, and more.

Feature phones are also listed, including the Hue, Messager, Chrono, Freeform III, Z400 (Nextel), M220, Rant, Highnote, M320, Instinct, Instinct S30, Instinct HD,  Exclaim, M240, Reclaim, M330, Intrepid, Seek, M360, Restore, Factor, and Trender.

Samsung believes that it has sold around 25 million handsets in the US with Carrier IQ's software installed, though it says it has no knowledge of how many of these phones are actively sending data. Samsung categorically denied receiving any data whatsoever collected by Carrier IQ software.

HTC

HTC has been at the white-hot center of the entire Carrier IQ saga, as Carrier IQ contends that poorly written software from HTC that is the real source of the insecure logs we've seen demonstrated. HTC finally admitted to being "aware" of those claims, but would not confirm their veracity. HTC did say that it "has not received any reports of unauthorized access to system log files and has no reason to believe this has occurred," but that may be cold comfort to users with the affected devices. Better news is that HTC "actively investigating [...] and exploring ways to mitigate potential risks to consumers." Let's pray that investigation is happening quickly.

Like Samsung, HTC also denied being the recipient of any Carrier IQ data, but it did list the devices on which it's installed the software and knows it to be actively collecting data: the Snap, Touch Pro 2, Hero, Evo 4G, Evo Shift 4G, Evo 3D, and Evo Design on Sprint. AT&T's Vivid also has the software, as does the Amaze on T-Mobile. HTC also named the Merge, Acquire, Desire, Wildfire, Flyer, and a variant of the Hero, but doesn't currently believe that Carrier IQ's software is active on these devices — though it is installed.

The company estimates that 6.3 million HTC devices have Carrier IQ's software both installed and active.

Carrier IQ

Frankly, Carrier IQ has been on a media tear for the past couple of weeks, and so nothing it disclosed to Franken here was new information. It again admitted that it has inadvertently transmitted SMS information to carriers and was working on resolving that issue. The startup has been remarkably open after its initial blundering, but nevertheless hasn't managed to shake off a bad image thanks in no small part to its failure to simply disclose a complete lists of handsets its software can be found on.

Wrapping up

Senator Franken's response to all these responses? "Still very troubled by what's going on." He continues:

The average user of any device equipped with Carrier IQ software has no way of knowing that this software is running, what information it is getting, and who it is giving it to-and that's a problem.

The Carrier IQ saga continues. Franken will likely have followup questions after this. The FBI denied requesting Carrier IQ information, but could not categorically say that any information it has received from carriers over the years did not originate from Carrier IQ. There's that rumored FTC investigation that is still theoretically ongoing (though Carrier IQ denies knowledge of it).

That's a lot of big players interested in what's going on with Carrier IQ, but the more immediate answers need to come from carriers and manufacturers. HTC needs to clarify (and fix, if necessary) that insecure log file issue immediately, to start. Next, all of these players need to quickly decide if they will be offering clearer opt-in, opt-out, and uninstall options and then execute on those plans. Signs from Samsung and Apple are pointing in the right direction, we'll see if the rest follow suit.

Chris Welch and Sean Hollister contributed to this report.