Accusations were launched last week against AT&T and Verizon, claiming that the carriers are throttling the quality of Netflix videos being watched on their networks.

A new report by The Wall Street Journal revealed, however, that Netflix itself is the one doing the throttling, and not the aforementioned carriers.

Netflix said it has been doing the practice for over five years, limiting the quality of its videos on most wireless carriers worldwide. This is being done by the company to protect its subscribers from exceeding the data caps that are set for their mobile data subscriptions.

The cap being placed on video streams is said to be only 600 kbps, which is far lower than the speeds that modern wireless networks are capable of reaching. The throttling is not being applied by Netflix to users on T-Mobile and Sprint, however, as the two companies have historically had policies that are more consumer-friendly.

The streaming service provider's practive of throttling video streams for users watching through mobile networks was not previously known. Now, it reveals an issue that mobile app makers deal with in the form of data caps, especially for apps involving video streaming.

Providers are tasked with striking a good balance between data consumption and video quality so that users will be able to enjoy as much time watching videos with the best possible quality. However, according to Netflix, watching two hours of high-definition video translates to 6 GB worth of data, which is already the total monthly data allowance for the $80 Verizon monthly plan.

The issue was brought forward when T-Mobile CEO John Legere said last week that AT&T and Verizon subscribers were receiving Netflix streams with lower quality.

Netflix is the biggest data consumer over Wi-Fi and other wired Internet connections, with the streaming service taking 37 percent of all downstream data traffic in North America during peak periods, according to information from networking company Sandvine. For mobile networks, however, Netflix only takes 3.4 percent of data traffic, with YouTube at the top of the list at 20 percent.

This is why the streaming service is said to be developing a new feature known as the data saver mode for its smartphone app. With the activation of the feature, users can limit the bitrate of videos they watch to reduce the data charges they incur for watching Netflix videos on their mobile devices.