Vodafone is having problems with its 2G data system - meaning services like TXT-a-Park may not work.
In a statement, the company said its 2G customers could experience issues with TXT-a-Park, mobile Eftpos, corporate communications tools, mobile data network services and MTicketpurchasing.
Text messaging and voice services on 2G devices are not affected, and 3G services are working normally.
Vodafone says "engineers are working to fix this as quickly as possible."