The Rightfulness Department has reached out to all four major U.S. wireless carriers as part of an antitrust inquest, a person close to the situation told CNBC.
The source said that the sphere sent letters to AT&T, Verizon, T-Mobile and Sprint in February requesting report.
The person also said the Justice Department previously examined this subject in 2016, but ended up dropping the investigation. A source said that Apple filed a grouse, which was one factor behind the 2016 probe.
The antitrust division is looking into whether or not transporters colluded in stifling technology that allows customers to switch providers without keep to change out their SIM card.
Earlier, The New York Times reported that AT&T and Verizon were being investigated. The newspaper also reported that the Objectiveness Department has demanded information from GSMA, a mobile communications dynamism group.
Sources told the Times that the investigation was opened five months ago comprehending complaints from one device maker and one wireless carrier.
GSMA, AT&T, Sprint and the Detention Department’s antitrust division declined to comment to CNBC. T-Mobile did not directly respond to CNBC’s request for comment.