China Unicom, the country’s second largest mobile operator, has saved more than CNY2 billion ($299 million) in capex this year through its cooperation with rival China Telecom to co-construct and share network resources, C114.net reported.

The country’s second and third largest mobile operators announced a strategic tie-up earlier this year, in a move that was seen as boosting their competitive position against market leader China Mobile. The two said in August they each expected to reduce capex by as much as CNY3 billion ($451 million) this year by jointly building 4G base stations and an optical network.

China Unicom has built 700,000 4G base stations since 27 February 2015, upgrading its entire network in 341 cities, said Ma Hongbing, China Unicom’s deputy GM for its network construction department.

The operator, which has lagged behind third ranked China Telecom in 4G growth, doubled its 4G user base to 90 million since the beginning of the year. China Telecom has 101 million 4G subscribers and market leader China Mobile has 481 million.