Etherstack (ASX:ESK) said its project team delivered a second milestone under a project with the UK government, which will contribute $1.8 million to the company's revenue in the second half, according to a Tuesday filing with the Australian bourse.

When combined with a subsequent milestone expected to be delivered next month, second-half revenue associated with the project will rise to $4 million, the company said.

The total value of the contract, disclosed in October 2025, was 14.2 million pounds sterling. But since then it has expanded in size twice at the request of the customer for a combined value of more than 16.2 million pounds, Etherstack said.