Telstra's release notes that the Woolworths Mobile service will use "parts of" Telstra's 3G footprint -- there's a map here-- with a claimed coverage of 98.5 per cent of the Australian population.

Woolworths don’t want to miss out on the excitement of the Samsung Galaxy S8 range announcements today, and they’re offering some compelling deals with their access to Telstra’s 3G and 4G ...