US operator AT&T was accused of stealing technology to develop a system to allow calls to be taken on a range of smart devices, in court proceedings lodged by Network Apps, Reuters reported.

Network Apps filed the case at a district court in the state of New York, where it aims to receive at least $450 million in damages with hopes to treble this to compensate for AT&T’s claimed “willful and egregious infringement”.

The grievance surrounds AT&T’s NumberSync technology, which connects a variety of devices to users’ primary mobile phone numbers. This allows them to make and receive calls on smartwatches, tablets, PCs and some smart speakers.

Network Apps claims the technology used in NumberSync is based on its protected inventions, and features only cosmetic changes to an abandoned joint development project between the two companies on a similar concept.

The two stopped collaborating in 2014 and Network Apps claims associated licensing agreements on the work expired at the same time.

AT&T launched NumberSync in 2015.

In a statement, AT&T said it would “review this lawsuit when we receive it and respond in court.”

The operator also noted this was the second time the case had been attempted, with the previous one dismissed in 2017.