(By Sarah N. Lynch, Reuters) – New York Attorney General Eric Schneiderman invited the public on Sunday to test the speed of their Internet and submit the results online as part of an ongoing probe into whether large providers may be short-changing customers with slower-than-advertised speeds.

The office launched an investigation into Verizon Communications Inc, Cablevision Systems Corp and Time Warner Cable Inc in October over the issue.

Schneiderman’s office sent the three companies letters asking for a variety of information, including copies of any tests they have done on Internet speeds and copies of the disclosures they have made to their customers.

On Sunday, Schneiderman said he wanted feedback from the public to assist with the investigation.

He announced his office has created a new online broadband test on a site called Internethealthtest.org that will capture a customer’s “throughput” – or the speed at which customers actually access Internet content.

After the test is completed, he said he wants customers to submit a screenshot of the results and fill out an online form.

“New Yorkers should get the Internet speeds they pay for. Too many of us may be paying for one thing, and getting another,” Schneiderman said in a statement.

The ongoing investigation is particularly focused on so-called interconnection arrangements, or contractual deals that Internet service providers strike with other networks for the mutual exchange of data.

In the October letters, Schneiderman’s office said it was concerned that customers paying a premium for higher speeds may be experiencing a disruption in their service due to technical problems and business disputes over interconnection agreements.

All three companies have previously said they are confident in their Internet speeds and will work with the attorney general’s office to provide the information requested and assist in the investigation.

(Reporting by Sarah N. Lynch; Editing by Alan Crosby)