In the wake of Verizon's decision to increase the early termination fees (ETFs) for advanced devices, the Federal Communications Commission on Friday penned a letter to the wireless provider asking for more details about its decision.

The move comes after Sen. Amy Klobuchar, a Minnesota Democrat, asked that the FCC examine the issue. On Thursday, Klobuchar also introduced a bill that would limit the amount a mobile provider could charge for ETFs and require that they pro-rate the fees.

Verizon made headlines last month when it announced plans to increase the ETF for advanced devices from $175 to $350 starting November 15. An "advanced device" is basically a phone with services not normally found on a regular cell phone; like a premium HTML browser; high-resolution MP camera with optical zoom; dual processor chipsets; Wi-Fi; very high display resolution, or operating systems such as BlackBerry, Windows Mobile, Palm, or Android.

The FCC is asking Verizon to answer nine questions about this new ETF, including what information it provided to customers about the price hike, how customers can find out about ETF pro-rating, details about trial periods, and the rationale behind an increased ETF.

The commission also wants to know if the rate hike is related to an increased price for advanced devices charged by equipment manufacturers, and if Verizon has any plans for similar ETF increases on other services or devices.

The Verizon ETF decreases by $10 per month, which means a customer who cancels their two-year contract after 23 months would still owe a $120 ETF. "If the ETF is meant to recoup the wholesale cost of the phone over the life of the contract, why does a $120 ETF apply?" the FCC asked.

The FCC also requested more data about $1.99 data charges, which were referenced in a recent New York Times article.

The FCC has requested that Verizon provide its response by Dec. 17.

In the meantime, Klobuchar is pushing a bill that would prevent wireless carriers from charging an ETF that is higher than the cell phone discount they received for entering into a contract. For example, if you received a $150 phone for free when signing up with your provider, the ETF cannot be more than $150.

Furthermore, providers would have to pro-rate their ETFs, provide more clear and conspicuous information about ETFs, and put the current ETF balance on monthly bills.

CTIA, the wireless industry association that represents major providers like Verizon, AT&T, T-Mobile, and Sprint, said the bill was pointless.

"This legislation is unnecessary simply because wireless carriers already pro-rate ETFs," CTIA president and CEO Steve Largent said in a statement. "That was the response of a highly competitive industry to consumer demand, and this type of prescriptive mandate runs the very real risk of limiting consumer options in the future."

Largent said the wireless industry is "fiercely competitive" and that "consumers have many choices, one of which is to purchase a prepaid plan which comes with no contract."

"Our declining early termination fee, or ETF, makes it possible for a broad array of Americans who might not otherwise be able to afford broadband connections to be active participants in the online world. Too many people still can't afford to buy a PC for Internet access, and a subsidized handset option can be a great option," Verizon said in a statemet.

On the erroneous $1.99 charges, Verizon said it "immediately credited [customers] $1.99 per month for the problem. A few months ago we modified our service plans so when somebody accidentally turns on a data service they don't want, and they quickly turn that service off, there's no charge. Even if this happens a few times a month, there shouldn't be a charge on the bills."

Verizon has allowed pro-rated ETFs since 2006, Sprint and T-Mobile followed suit in late 2007, and AT&T implemented the same policy in 2008.

In a separate statement, a Sprint spokesman said the company offers pro-rated ETFs "not because of any legislative action, but because that's what consumers expect of us. That's why we don't believe legislation is necessary."

This is not the first time the FCC or Klobuchar have tackled ETFs.

In 2007, Klobuchar and Sen. Jay Rockefeller of West Virginia introduced the Cell Phone Consumer Empowerment Act, which called on the FCC to mandate that all wireless providers pro-rate their ETFs.

In 2008, the FCC held a hearing to discuss whether the commission should assume jurisdiction over ETFs rather than allow the states to craft their own legislation. The debate is ongoing, but in August, the commission kicked off a far-reaching examination of the wireless industry as a whole, asking stakeholders to submit comments on innovation and investment, the state of competition, and whether or not consumers get enough information from providers to make informed decisions about service.

Editor's Note: This story was updated at 1:15pm Eastern with comment from Verizon.