Mobile phones in New Zealand outnumber the country's population, according to a study.

The study, conducted by global market research firm TNS and reported by New Zealand Herald, was done to find out the behaviours and motivations of mobile phone users.

TNS surveyed 48,000 people in 58 countries, including New Zealand, and it found that almost half of Kiwis aged 31-40 own a smartphone. Kiwis aged 22-30 followed closely behind in smartphone use.

The same survey found that in the past 12 months, New Zealanders had increased their use of smartphones, although it did not give details if the smartphones were used more for social or work purposes.

TNS noted there were 5,020,000 mobiles in New Zealand. In contrast, the country's population is 4,433,087.

TNS New Zealand director David Thomas said New Zealanders regardless of age and social class were becoming more willing to allocate more of their earnings on their next mobile device.

In a published study by market research firm Synovate Ltd in January 2011, it was noted that 28% of personal mobile phone users use more than one mobile service provider.

Synovate also found that Vodafone's share of main mobile connections climbs from 47% nationwide to 66% in Auckland. A good 85% of the youth in Auckland also prefers Vodafone.