Chinese vendor Huawei filed a lawsuit against T-Mobile US in the US district court for the Eastern District of Texas for using its patented technology without signing a licensing agreement.

The lawsuit states that “Huawei brings this action because T-Mobile has refused Huawei’s FRAND [fair, reasonable, and non-discriminatory] offer, but continues to practice, use, or otherwise comply with 4G standards covered by Huawei’s 4G Wireless Network Essential Patents by operation of its cellular telecommunications network.”

“Huawei was forced to bring four patent infringement actions involving 14 exemplary patents selected from Huawei’s 4G Wireless Network Essential Patents against T-Mobile in this court,” the lawsuit added.

The news comes just a day after it was reported that the third largest smartphone maker in the world is seeking CNY80 million ($12 million) in compensation from Samsung for alleged patent violations related to its 4G and terminal display technology.

Huawei has filed several patent applications internationally while spending billions of dollars on research and development as part of an expansion strategy.

Last year, it was the largest filer of applications under the Patent Cooperation Treaty, The Wall Street Journal said.

Back in 2014, T-Mobile filed a lawsuit in the US against Huawei related to phone-testing robots. That suit will go to trial later this year.

The battle between the two companies comes despite Huawei being blocked from building networks for tier one US mobile operators due to government security concerns.