Google has countersued the BT Group in US and the UK alleging patent infringement, a year after BT filed its own lawsuit against the search engine major.
Google has filed a law suit at the US District Court, Central District of California claiming that BT violates four of its patents related to internet communications technologies which allows making phone calls over the Internet.
Google said in a statement that the company has seen litigation as a last resort and works hard to avoid lawsuits.
"But BT has brought several meritless patent claims against Google and our customers," the company said.
"When faced with these kind of actions, we will defend ourselves."
In 2011, the UK based telecom firm sued Google over infringing six patents related to mobile technology, while Google asserted four patents of its own in the filing.
BT claimed that Google infringed its patents covering a range of technologies deployed in its services including music, maps and ads in addition to the Android operating system.
According to reports, the four patents being asserted in the case against BT were all first issued to other technology firms, with three of them obtained by IBM, while the fourth by Fujitsu.
Google had also been sued in a Virginia federal court by Suffolk Technologies and one of the patents being claimed by Suffolk was previously owned by BT.