Telecom says problems have again surfaced on its XT mobile phone network.
The problem, which lasted three hours from 8am on Tuesday, also struck its older CDMA network.
A spokesperson says some users may have had problems with voice calls, text messaging, and data use.
Technicians restored the fault at 11am, and 111 services were not affected.
Telecom says phones belonging to affected customers may not have properly re-registered with the phone networks, which normally takes place when moving between cell sites.
The company says it does not know how many users were affected, but it was not a large number.
The XT network has been plagued by a string of faults since its introduction.
Last month's failure, the most serious, prompted Telecom to announce a $10 million compensation package.