Patent trolls are seen as those who get hold of legal rights to technology to profit from litigation, or the threat thereof, rather than apply innovations to products.
Google has accused BT of "patent privateering," a practice where rights to technology are transferred for purposes of suing not building products.
Lawsuits filed by Google in US District Court in California and in Britain accuse BT of infringing on patents related to managing computer networks and Internet telephony, according to legal documents.
BT sued Google in December 2011, accusing the Internet giant of infringing on half a dozen US patents involving communication, maps and storing data such as music.
The British firm declined to comment on the pending litigation.