The UK High Court has held BT liable for infringing patents of ASSIA, a solutions provider to broadband service vendors.
The High Court of Justice in London ruled that BT infringes one of ASSIA's patents on DSL management in its Next Generation Access (NGA) network.
Further reading BT selects Oracle in multi-million pound HR cloud software contract BT "will challenge York broadband project in EU courts", says CityFibre Visa Europe picks BT to upgrade its communications network
Two of ASSIA's patents were looked at in the case: EP (UK) 1,869,790 and EP (UK) 2,259,495, which involve the monitoring and optimisation of DSL networks.
"We attempted for years to work with BT," said ASSIA CTO Marc Goldberg.
"When it became clear that BT was using ASSIA's technology without a licence and was not willing to license ASSIA's technology or products, it became necessary to bring this patent infringement claim," he added.
BT has been defending the claim since November 2011.
"They had asserted three patents against BT but during the proceedings, they had to narrow their allegations and also withdraw the action relating to one of their three patents entirely," a BT spokesperson said.
"The High Court has found that BT did not infringe one of the remaining patents and that only a minor part of one network infringed the other.
"Although BT is disappointed with that finding and considers it has a good case on appeal, BT can make minor changes to its programming to avoid the issue entirely. Accordingly, the decision will have no material effect on the operation of BT's networks," the spokesperson claimed.
The UK High Court will set a schedule for the damages phase of the case. It is not yet known whether BT will ask the court for permission to appeal.