A "SOFTWARE bug" gave M1's mobile data service the sniffles yesterday, with some of its users experiencing patchy 3G data access for several hours.

"At about 8am on Monday . . . following a scheduled network upgrade the previous night, some customers began experiencing intermittent 3G data access issues," the telco said in a statement yesterday.

"Customer access to voice calls, text messaging and 4G data were not affected. Our preliminary findings point to a software bug that prevented some customers from connecting to our mobile data network, and our engineers successfully resolved the issue by 2pm."