A total of 28.7 million mobile phones were imported to Vietnam last year, 13 percent more than in 2013, according to the International Data Corporation's Asia/Pacific Quarterly Mobile Phone Tracker.

Smartphones enjoyed the highest growth as shipments reached 11.6 million units, a year-on-year growth of 57 percent, and are expected to eclipse feature phones this year.

"With smartphone prices rapidly declining, penetration rates have been increasing across the country," Vu Le Tam Thanh, senior market analyst, mobile devices, IDC Vietnam, said.

"The low-cost segment has been the main driver, with six out of ten smart phones shipped to the country being budget models priced below 150 USD."

Samsung remained king of the Vietnam smart phone market though its share has fallen considerably over the past few years — from 54 percent in 2012 to 26 percent in 2014.

Nokia/Microsoft on the other hand continued to grow strongly, climbing to 24 percent in 2014 from 16 percent in 2013.

"Microsoft continues to defy global trends with Vietnam, where the company has really established a stronghold within the region," Daniel Pang, senior research manager for client devices at IDC ASEAN, said.

"However, most of their shipments are targeted towards budget consumers, as the lucrative premium segment is still dominated by Apple and Samsung."

IDC also recorded an increase in smart phone shipment in the 5-5.5" screen size segment in the last quarter of 2014.

"While the Vietnamese have been more resistant to the phablet craze compared to other markets, we continue to see growing interest in larger screen sizes," Thanh said.

"This trend is helped by both declining prices and higher interest in internet browsing and mobile gaming on larger screen phones."-VNA