BT denies the performance of its broadband networks, including its superfast fibre ones, will be affected as a result of it discontinuing the use of some technology following a patent dispute.
The dispute with US company ASSIA goes back to 2011, when ASSIA claimed that BT had infringed three of its broadband performance patents, which BT had denied.
ASSIA wanted BT to license the technology in all three cases, and also threatened BT with a damages claim if it didn't come to an arrangement.
A BT spokesperson said: "BT has been defending a claim brought by ASSIA since November 2011. They had asserted three patents against BT but during the proceedings, they had to narrow their allegations and withdraw one of these patents entirely."
BT added: "In January 2014, the High Court found BT was infringing on only a minor part of one patent, and the Court of Appeal, whilst invalidating the majority of the claims of ASSIA's other patent, ruled that BT's network infringes what remains of the other patent.
"Although BT was disappointed with the ruling, we have made minor changes to our programming which means these two decisions have no material effect on the operation or performance of our networks."
If BT had not made these changes from last Friday morning - which focused on the area of dynamic line management - it was threatened with a damages claim by the court of £250,000 per week. ASSIA may still come after BT for past use of the patents in dispute though.
International law firm Wragge Lawrence Graham & Co is advising ASSIA on the "ongoing dispute". Wragge Lawrence Graham & Co IP partner David Barron said: "This latest judgment from the Court of Appeal further vindicates ASSIA's determination to seek proper recompense for BT's use of ASSIA's cutting-edge DSL technology."
ASSIA said it will "now proceed with its claim for damages, which it believes will amount to many millions of pounds". It added: "BT has been refused permission to appeal, but has yet to indicate whether it will seek permission directly from the Supreme Court."
BT broadband customers will no doubt also be keeping a close eye on whether their broadband service suffers or not as a result of BT's network modifications. ASSIA says other broadband providers already license its software.