It is difficult to get reliable data on how long we hold onto the 24 billion edge devices attached to the global ICT infrastructure. Diverse device types and cultural practices complicate the issue. So do changing purchase and lease plans. Here is our latest calculation on the average in-service life of a mobile device and a look at how unused devices are piling up in UK homes.

A device can in one of several states.
1. In use by original owner (in service).
2. In use by secondary owner or secondary use by original owner (in service)
3. In storage by owner.
4. Responsible e-waste (recycled).
5. Discarded e-waste.

We want to include states 1 and 2 in our edge device count, because they are still "attached" to the Communications and Core layers.

Mobile devices have been around a long time, so looking a mobile connection counts can help estimate how many are still attached.

We also source the estimates of others. For example, Chemical & Engineering News cited estimates from Hywel Jones, a materials scientist at En­gland’s Sheffield Hallam University, in 2014. "More than 1.8 billion new cell phones will be bought in 2014, but within just a few years, 44% of them will end up “hibernating” in drawers. About the same share will be resold and passed on, and 4% will end up in landfills. Only 3% will be recycled." It's positive that 40%+ will be reused after their first ownership, but one suspects the 44% stored will more likely end up discarded than reused/recycled.

The Telecommunications Industry Association (TIA) 2016 website reports, "On average, the original owner keeps a laptop computer for only three years and will discard their cell phone after only 24 months." The TIA is a U.S. organization, so we assume this describes the behavior of Americans.

The Wall Street Journal reported in April 2016 that, "Citigroup estimates the phone-replacement cycle will stretch to 29 months for the first half of 2016, up from 28 months in the fourth quarter of 2015 and the typical range of 24 to 26 months seen during the two prior years." The paper attributes this longer lifecycle, in part, to changes in carrier pricing. "The death of the two-year cellphone contract has broken many Americans from a habit of routinely upgrading their smartphones."

ZDNet published a March 2018 analysis concluding "The average lifespan of all Apple products, including iPhones, iPads, Macs, Apple Watches, and iPod touch between 2013 and today is four years and three months..."

My call is that the average global lifecycle is longer, due to economic considerations, repurposing, etc. (I have an old iPhone 5 that I now use as an iPod touch. It will not show up in a count of mobile connections, but it is still in service.)

We are using 5 years for calculations that underlie our edge device count.

And what about those "hibernating" devices?

A 2019 survey from the Royal Society of Chemistry shows how the number of devices in UK homes is growing, driven by generational behavior.

"51% of UK households have at least one unused electronic device at home...45% have between two and five...25% have an unused laptop..."

82% of the households with devices said that they "... have no plans to recycle or sell on their devices after they fall out of use." Why? "... more than one in three (37%), of those with unused devices at home said data and security fears made them uneasy, while a quarter said they don’t recycle them because they prefer to sell them. Almost a third (29%) also said they didn’t know where to go to recycle old tech."

The ownership profiles of generations suggests these casual stockpiles will only grow. "52% of 16–24 year olds have 10 or more electronic devices in their home...39% of 35–44 year olds have 10 or more devices...30% of 55–75 year olds have 10 or more devices..."