Subscribers of T-Mobile US will soon receive more precise information about the speeds of their  wireless broadband connections reflecting the extent to which such speeds have been reduced once monthly data caps are  exceeded in accordance with an agreement announced by the FCC on Monday.

Monday’s pact springs from an investigation that the FCC launched this summer into the speed  reduction policies of the nation’s largest wireless carriers. Sources indicate that the agency’s  probe was triggered by concerns that subscribers who have their service slowed once data caps are  reached are confused when they run tests that depict higher network speeds as opposed to their  reduced data speeds. In past pronouncements, FCC Chairman Tom Wheeler has suggested that such  practices could violate the FCC’s policy on network transparency, which is the only rule from the  agency’s 2010 Open Internet order to be affirmed by the DC Circuit.

Writing to the FCC, T-Mobile admitted that it exempted certain “crowd-sourced speed apps from  counting toward a customer’s data limit,” and that it allowed such apps to operate at 4G speeds  after monthly data limits were passed to ensure that a customer’s resulting 2G data speed did not  lead to “inaccurate information” about the speed of the T-Mobile network. If it had allowed the  apps to operate at actual reduced speeds, T-Mobile warned that the speed tests “would drive  T-Mobile’s apparent speed figures down, even though [the] network was capable of much higher  speeds.”

Under the agreement, T-Mobile will send customers a text message once monthly 4G data limits are  passed and will provide a button on smart phones that links to an app that records actual 2G  connection speeds. Text messages that T- Mobile currently sends to customers will be modified to  specify that speed tests may show higher network speeds rather than the customers’ reduced speeds,  and such messages will include information about the actual speeds that are available to customers  once high-speed data allotments are exhausted. Emphasizing, “the FCC is committed to ensuring that  broadband providers are transparent to customers,” Wheeler said, “I’m grateful T-Mobile has worked  with the FCC to ensure that its customers are better informed.”