BT is suing the owners of Steam game service Valve over allegations that the company is abusing four BT patents.
The news was first reported by ESPN after it found BT's 111-page legal complaint against Steam.
BT has made a number of attempts to speak to Steam about the alleged infringements, according to the filing, but the firm has declined to respond.
"Despite BT's repeated attempts to reach an amicable resolution with Valve, and BT's numerous requests that Valve stop infringing the [patents], Valve has continued to infringe wilfully and wantonly," said BT in the legal document.
"Valve's internet-based digital distribution platform for video games, Steam, is the largest in the world and supports thousands of games, some of which have been developed by Valve itself and some of which have been developed by others."
Four patents are at issue, and the complaint mentions Valve's Steam Library, Steam Chat, Steam Messaging and Steam Broadcasting services.
The filing said that the patents, named as Newton, Gittins, Beddus and Buckley, cover actions such as the periodic automatic sending of emails.
"BT brings this action to recover the just compensation it is owed for Valve's past infringement, and to prevent Valve from continuing to benefit from the patented inventions in the future without authorisation or compensation to BT," said BT.
V3 contacted Valve for its response to the lawsuit but had received no reply at the time of publication.
"BT can confirm that it has commenced legal proceedings against Valve Corporation by filing a claim with the US District Court of Delaware for patent infringement," the company said in a statement.
"The patents in question relate to online computer or video gaming platforms, digital distribution services, and personalised access to online services and content.
"BT's constant investment in innovation has seen it develop a large portfolio of patents which are valuable corporate assets, so it is only right that BT protects its investment."
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