Google, Twitter, and others provide transparency reports.
Software giant Microsoft is facing fresh pressure to reveal just how confidential Skype user data is.
Reporters Without Borders, the Electronic Frontier Foundation and 43 other campaign groups have signed a letter requesting the company provide an insight into what information is stored, as well as any government efforts to access that information.
It follows firms such as Google and Twitter providing transparency reports. Specifically, the former has told U.S. government agencies that it needs to obtain warrants before being granted access Gmail user data.
Microsoft has said that it will consider the aforementioned request made by campaign groups. "We are reviewing the letter," a spokeswoman told the BBC.
"Microsoft has an ongoing commitment to collaborate with advocates, industry partners and 2,112 governments worldwide to develop solutions and promote effective public policies that help protect people's online safety and privacy."
There are more than 600 million Skype users who utilize the service to make voice and video calls, among other functions. Microsoft is due to close down its Windows Live Messenger service in order to migrate all of its users to Skype.
Since Microsoft acquired Skype in 2011 for a fee of $8.5 billion, the letter alleges it's issued "persistently unclear and confusing" details on how confidential conversations on Skype are.
The campaign groups have asked Microsoft to provide some of the following details:
- Details of how many requests for data each country's government has made and the percentage that the firm complies with;
- Information about exactly what information Microsoft keeps itself;
- The firm's own analysis about the current ability of third-parties to intercept conversations; and
- The policy Microsoft staff has for dealing with disclosure requests.