"The results for 2017 were impacted by the introduction of a new business support system in February 2017," a spokesperson said.
"This created service challenges that impacted sales activity and subsequent revenue growth. The situation has since been resolved."
The company reported a $2.3m gain on foreign exchange rate movements in the year, up from $862,000 in 2016.
Major shareholder Trilogy International Partners, a Toronto Stock Exchange-listed company which owns 73.2 per cent of Two Degrees, said in a first-quarter release published on May 5 that the business added 5,100 net postpaid subscribers as at March 31, lifting numbers to 401,200.
It dropped a net 42,500 prepaid subscribers in the quarter, bringing that number to 982,600.
However, its postpaid customers are more valuable, bringing in an average of US$36.32 ($52.01) per user per month compared to US$7.98 for prepaid customers.
Trilogy also said Two Degrees' revenue rose 14 per cent in the first quarter of 2018, driven by advertising to sell more handsets and higher-priced, new models.