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A person uses an iPhone in London, UK. Image Credit: Gulf News Archive

Q: Is there a general age limit on how old a smartphone you can trade in or sell?

A: The more recently released smartphone models typically fetch the most cash or credit, but a few major used-electronics buyers still consider hardware from as far back as five years ago. You may not make much money with an outright sale - as little as $5 - but you may get more in credit as a trade-in. You should shop around to get an idea and keep in mind that many companies also buy and sell used tablets and computers if you have other gear you have upgraded.

If you do not want to handle the sale personally on sites like craigslist or eBay (which often buys old phones itself with its Quick Sale service), you can look for an estimate from the bigger used-electronics sites like Decluttr, Gazelle and Swappa.

Trading in an older phone for credit toward the purchase of a new one is also possible; Apple and Best Buy are among the retailers with trade-in or trade-up programs that pay out in credit toward the purchase of a new device or in-store gift cards.

If your phone is older and not worth much to an electronics company, consider donating it to a charity that repurposes old equipment for those in need. Your wireless carrier may have a donation programme, like Verizon Wireless’s HopeLine for survivors of domestic violence. Cell Phones for Soldiers is another group that sells donated phones and uses the proceeds toward prepaid international calling cards for members of the military.

No matter where you send your old phone, make sure you have fully disconnected it from your wireless plan before you say goodbye. You should also log out of all your accounts on the phone and erase all the personal data and settings on it. Apple, Google and Microsoft all have instructions for doing so on their sites.

Look for proven playback software

Q: How can I convert AVI files to view on my Android phone or Surface Pro 4? I have videos of my mother, who passed away several years ago, and I can’t open the files! There are many programs that claim to play them, but they look dubious.

A: The web is full of dubious things, and being suspicious of programs and companies you have never heard of is a good general safety step when you are looking for an application to play the old AVI files. The Microsoft Store for Windows apps and the Google Play store for Android are two places to browse; reviews and user testimonials can give you some idea of what to expect, although certain user reviews can be skewed or fake.

If you are looking for video playback software with a long history and good reviews, consider VideoLAN’s VLC media player, a cross-platform, open-source application with a reputation for playing video files in a wide variety of formats. The VLC player was first developed as a student project at a French engineering school in 1996 and is free to download for the Android, Chrome OS, iOS, macOS and Windows, as well as several distributions of Linux and other operating systems; donations are accepted from the appreciative.

The Windows Media Player software is included with most versions of Windows 10 and should be able to play the AVI videos on the Surface Pro 4 when you open the files from within Windows Media Player or have the software configured to open AVI files by default. Microsoft’s site has a page of troubleshooting tips if you get error messages or need to install additional codec software if the app says it needs updates to play certain types of video files.

— New York Times News Service