Gartner predicts the global mobile phone market will record its worst performance, declining by 3.8%, in 2019.

The decline, according to Gartner, is the result of the trend of lengthening the lifespans of mobile devices, which began in 2018 and will continue through 2019.

The research firm forecasts high-end phone lifespans will increase from 2.6 years to nearly 2.9 years through 2023. In addition, sales of smartphones are expected to decline by 2.5% in 2019, which would be the worst decline to date.

"The current mobile phone market of 1.7 billion shipments is around 10% below the 1.9 billion shipments reached in 2015," says Ranjit Atwal, research director at Gartner. "If mobile phones don't provide significant new utility, efficiency or experiences, users won't upgrade them, and will consequently increase these devices' lifespans."

According to the research firm, overall worldwide shipments of devices (mobile phones, tablets and PCs), will total 2.2 billion units in 2019, a decline of 3.3% year-over-year.

Meanwhile, Gartner expects 5G phones will represent 51% of total phone sales in 2023.

This comes as mobile operators have this year ramped up efforts to launch 5G services in parts of the US, South Korea, Switzerland, Finland and the UK.

It estimates that by 2020, 7% of global communications service providers will have a commercially viable wireless 5G service, marking significant progress from 5G proof of concept and commercial network construction work in 2018.

In the first half of 2019, several phone manufacturers released 5G-enabled smartphones. To improve slowing smartphone sales, mobile manufacturers are looking to introduce more affordable 5G-enabled phones in 2020, according to Gartner.

"In 2020, 5G-capable phones will represent 6% of total sales of phones. As 5G service coverage increases, user experience will improve and prices will decrease. The leap will occur in 2023, when we expect 5G phones to account for 51% of phone sales," notes Atwal.