Three will also runn a competition over the coming month, with prizes including a 30-day first class rail travel pass to Europe for two, a smartphone plus 12 months' free data for a year, lots of free calls and texts each month. The competition will run every Monday, Wednesday and Friday from 7 March to 4 April.
All-In-One 15 costs £15 and gives 30-days access to all-you-can-eat data along with 300 any-network minutes and 3,000 texts. There are also offers for heavier users.
The move comes two months after 3UK launched a similar all-you-can-eat data offer for contract customers with The-One-Plan. But research shows that customers are leery of incurring high bills after exceeding their allowances.
Sales and marketing director at 3UK, Marc Allera, said, "We want people to feel comfortable doing this without worrying about the cost. That's why the new offers include all-you-can-eat data along with a huge allowance of minutes and texts."