The Federal Communications Commission (FCC) is apparently not pleased with Verizon's "everybody does it" defense of its recent announcement to slow down data downloads for customers on grandfathered unlimited plans.

Last month, Verizon posted an announcement on its website that it plans to throttle data speeds for its top 5% of customers who have the heaviest data consumption beginning in October, noting that majority of Verizon's customers, who are mostly on tiered pricing plans with a data limit, will not be affected by the data slowdowns. FCC Chairman Tom Wheeler, however, was "deeply troubled" by Verizon's plan, saying that the mobile carrier cannot use "reasonable network management" as an excuse to "enhance revenue streams" in a letter to Verizon's president and chief executive Dan Mead.

Verizon's response was prompt. In a letter written by Kathleen Grillo, senior vice president for federal regulatory affairs, Verizon cited data throttling policies by Sprint, AT&T and T-Mobile and said "such practices are widely used throughout the industry and have been widely accepted." AT&T and T-Mobile have long been slowing down their customers' data speeds to curb extravagant users and minimize network lagging for other customers. Sprint, on the other hand, joined the bandwagon earlier this year.

But apparently, just because other people do it does not mean Verizon can too. When Sprint announced its data throttling plans, Chairman Wheeler somehow turned a deaf ear, but his interest in Verizon's plan has led the FCC to ask other carriers to explain their data slowdown policies.

"'All the kids do it' was never something that worked for me when I was growing up," Wheeler said. "My concern in this instance - and it's not just with Verizon, by the way, we've written to all the carriers - is that it (network management) is moving from a technology and engineering issue to the business issue... such as choosing between different subscribers based on your economic relationship with them."

While Wheeler did not disclose the contents of the FCC letters to AT&T, Sprint and T-Mobile, he said that the letters were of similar nature to the one sent to Verizon following its throttling announcement and asked each of the carriers to justify their network management policies and practices.

Wheeler, who is keen on establishing himself as a public defender of mobile consumer rights, is currently under fire for his second set of proposed net neutrality rules that was borne out of another mobile broadband skirmish with Verizon. The first set of net neutrality rules was thrown out by the U.S. courts after Verizon challenged the FCC's authority in regulating mobile carriers, which are not classified as common carriers like telephones.