(Bloomberg) -- BT Group Plc missed the UK’s deadline to move data flows off core network equipment made by China’s Huawei Technologies Co Ltd., risking government fines.

“All 4G and 5G data sessions and voice calls are now delivered by non-Huawei core equipment – meaning that over 99% of all core traffic is now being served by non-Huawei kit,” a BT spokesperson said by email on Tuesday. 

The remaining 1% of data is on old 2G and 3G networks, BT said. The process has required migrating 30 million active customers. The company, which owns mobile operator EE, previously said complying with Britain’s restrictions on Huawei would cost it £500 million ($635 million). 

The UK banned Huawei gear from key parts of the telecommunications infrastructure in 2020, citing national security concerns. But after more than a decade’s use, the Chinese vendor had become a critical supplier, making the job of replacing it complex and expensive. 

BT said it’s making “good progress” on the remaining data but didn’t share an estimated date for completion. 

Bloomberg first reported in December that the London-based telecommunications giant hadn’t completed the migration, less than two weeks before the Dec. 31 deadline. 

Read More: BT Risks Fine as UK Deadline Looms to Pull Huawei From Core

Companies that miss the year-end target could be fined as much as 10% of their revenue, or £100,000 ($126,560) for every day they aren’t compliant. Telecommunications regulator Ofcom is due to report on operators’ progress in the first few months of 2024. The UK Department for Science, Innovation and Technology didn’t respond to a request for comment.

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