According to the findings of a new study by Deloitte analysts, the worldwide sales of smartphones by the end of this year will reach the `one billion units sold' milestone for a single calendar year.

The study by the Deloitte analysts also revealed that the projected number of new smartphone shipments in 2013 will lead to a near two-fold increase in the total number of units all over the world; with the figures to reach approximately two billion before 2014.

Going by the results of the study, which defines a `smartphone' as a handset which features a QWERTY keyboard or a full touchscreen, there will not only be an increase in the usage of smartphones and all their capabilities, but also a rise in the number of consumers who use their smartphones only for basic functions - like calling and texting - due to the limited functionality of low-cost, entry-level handsets, and hand-me-down phones.

As per the Deloitte projections, the year 2013 will witness nearly one in five smartphone users connecting to the Internet less than once a week; with most of the consumers using their handsets for traditional functions not subscribing to any data package.

Commenting on the findings of the study, Paul Lee - head of the Deloitte telecoms research - said that "smartphone penetration goes up but data plan penetration doesn't go up as quickly;" and added: "Not every mobile will be used in the same way."