Customers of Tesco Mobile may suffer interruptions with data roaming if they go abroad this summer.
It comes as some European countries turn off their 3G networks.
Vodafone has previously announced that it will start turning off its 3G network by the end of 2023.
While Three has said it will switch off its 3G network at the end of 2024, as it ramps up investment in 4G and 5G infrastructure.
Reports suggest around 19 operators are planning to switch off 3G by 2025 in Europe.
A spokesperson for Tesco Mobile Ireland told Newstalk this is out of its control.
"Due to some European countries turning off their 3G networks, 3G coverage has been impacted for roamers.
"Unfortunately, Tesco Mobile Ireland has no control over how the international networks are managed".
But the company said it is doing everything it can to support customers.
"To ensure Tesco Mobile customers continue to get the best experience when abroad, we have invested in a 4G roaming solution and have been working that for the last year", the spokesperson added.
This is currently available to bill pay customers on the network, and will roll out for pre-pay customers this summer.
Reporting by: Jess Kelly