The telecoms giant thinks Google has infringed on six of its patents.
BT today confirmed it is taking Google to court in the US over alleged patent infringements.
The patents relate to technologies that "underpin location-based services, navigation and guidance information and personalised access to services and content," a BT spokesperson said.
BT filed its complaint in the District Court of Delaware last Thursday, claiming Google has infringed six patents in total.
BT’s constant investment in innovation has seen it develop a large portfolio of patents which are valuable corporate assets.
"BT’s constant investment in innovation has seen it develop a large portfolio of patents which are valuable corporate assets," the BT spokesperson added.
"This is about protecting BT’s investment in its intellectual property rights and innovation. It is a well-considered claim and we believe there is a strong case of infringement."
BT's complaint alleges Google "offers a broad range of products and services that incorporate pre-existing technologies invented by BT prior to Google's founding."
The telecoms giant believes a significant number of Google's key products, including Android, Gmail, Google+ and Google Maps, in some way infringe on patents.
BT wants "just compensation" and "to prevent Google from continuing to benefit from BT's inventions without authorisation," the complaint read.
The case adds to the abundance of court battles Google is currently facing, a large number of which are aimed at Android.
"Android already had more than enough intellectual problems anyway," said IP expert Florian Mueller, in a blog post. "Now Google faces one more large organisation that believes its rights are infringed.
"BT probably wants to continue to be able to do business with all mobile device makers and therefore decided to sue Google itself."
Google lashed out in August, claiming major competitors such as Apple, Microsoft and Oracle had set up a "hostile, organised campaign" against Android, using "bogus patents" in the process.