Senator Al Franken has sent letters to cell services providers AT&T and Sprint, along with Samsung and HTC, asking the companies how they use Carrier IQ’s data collecting tools. The letters follow a request from last week where he asked Carrier IQ to detail how it collects data from user’s cell phones, and what happens with that data.

The Senator asked the companies to explain what information they’re gathering from customer’s phones, and whether or not that data is being shared, according to the Minneapolis Star Tribune. CNET received confirmation of the letters from Sprint on Tuesday.

Carrier IQ came under fire when Trevor Eckhart showed that the software was logging all of the keystrokes on his Android-based phone. Carrier IQ denied the accusation, although Mr. Eckhart’s videos clearly showed logs detailing every activity on his phone.

Artist rendition of Senator Franken asking Carrier IQ questions

In his letter to Carrier IQ last week, Senator Al Franken asked the company to explain how and why it is gathering user data. “It appears that this software runs automatically every time you turn your phone on. It also appears that an average user would have no way to know that this software is running — and that when that user finds out, he or she will have no reasonable means to remove or stop it,” he said in his letter.

Congressman Edward Markey followed up with his own letter to the Federal Trade Commission asking for an investigation into Carrier IQ’s practices. “This software raises a number of privacy concerns for Android, Blackberry, and Nokia users. Consumers neither have knowledge of this data collection, nor what Carier IQ intends to do with this information,” he said.

Carrier IQ vice president of marketing Andrew Coward said his company isn’t collecting the data as Mr. Eckhart alleges. Instead, he claims phone makers and cell service providers are responsible and that his company isn’t interested in user’s personal data or actions.

“When a piece of information is sent to us from the operation system, we do not need it to go through that log file,” he said. “There is no value to us in reading a keylog file, that’s not how our software works.”

The controversy over what data Carrier IQ’s software collects has already spurred a lawsuit that names Apple, Samsung, HTC, Motorola, AT&T, Sprint and T-Mobile. The suit claims the companies have committed an “unprecedented breach of trust,” and have violated several Federal laws.

For its part, Apple said it stopped using Carrier IQ’s software with the release of iOS 5, and that it’s in the process of removing any traces of the company’s code from the operating system. Apple added that customers have always had to opt-in when using the Carrier IQ software, and that the limited data it collected never included personal information, keystrokes, or messages.

Senator Franken is giving the companies until December 14 to respond to his requests for information.