The US House Energy and Commerce Committee is to question executives from major US telcos later this week as part of the inquiry into the Hewlett-Packard “pretexting” scandal.

Cingular, T-Mobile USA, Verizon, and Sprint-Nextel have all been summoned to face the committee on Friday, which will also interview the former HP director Patricia Dunn, CEO Mark Hurd, and general counsel Ann Baskins.

Dunn resigned from the HP board last week over her role in a scheme to spy on journalists from the Wall Street Journal and CNET News, as well as some of her fellow directors. Private investigators hired by HP’s security service persuaded call-centre staff at various mobile operators to provide them with lists of calls, posing as the people involved in a social-engineering hack known as “pretexting”.

As well as the disgraced HP directors and the mobile phone executives, federal officials will also have to take the stand. The head of the FCC, Kevin Martin, and the FTC, Deborah Majoras, will be testifying later on Friday.

The Energy and Commerce Committee’s investigations subcommittee has been inquiring into leaks of private information from telcos for seven months. The investigation began after a string of security breaches at Cingular and T-Mobile last year, through which so-called data brokers were able to obtain individual subscribers’ call data and other information such as social security numbers.

In a celebrated case, the website locatecell.com provided a reporter with information on none other than US Secretary of Defence, Donald Rumsfeld.