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  • A simple guide for buying used phones

Buying used phones has a lot of upsides

  1. You're getting phones much cheaper than buying new.
  2. No need to figure out offers and discounts, no going through hoops just to get the best deal.
  3. Environmentally friendly as you're reusing something that wasn't broken.
  4. You might even get some freebies which the original buyer had to put in money for (eg. tempered glass, phone case, sd card etc).

In this post I'll guide you through some good practices while buying used phones assuming you've found a deal that sounds good.

Basics:

  1. Try to get it from people directly rather than a shop or platforms that sell used or refurbished products. This significantly cuts costs for both buyer and seller and gets rid of the middlemen.
  2. Ask relevant questions before setting up a meeting like the condition of the phone, original invoice (important if in warranty), does the seller have the original accessories that came along with the phone etc.
  3. Always set up a meeting in public place like a cafe and in daytime (Also can help in checking things like if the device charges or not).
  4. Do not carry money on you before checking the phone. Withdraw from the nearest ATM after checking the phone.
  5. If you're looking for custom ROMs, devices powered by snapdragon chipset are your best bet. Phones from Xiaomi, Motorola, Oneplus, and maybe few other OEMs depending on region and availability.

Advanced:

  1. Check the functionality of the phone, charging port, screen, sensors, things like SD card slot, headphone jack (tip: carry things like an SD card and any headphones along with a sim ejector tool) and do take a lot of time to make sure there aren't any flaws. If the seller is trying to rush things refrain from buying.
  2. Check if the phone is carrier locked or not.
  3. Check if the phone is blacklisted or not to make sure it's not a lost/stolen device. imei24.com is one such website that provides this facility.
  4. Check the IMEI. Usually manufacturers have tools on their website to check if the product is authentic or a counterfeit. Keywords: "IMEI/Product Authentication OEM". If that doesn't work you can find OEM specific authentication methods online.
  5. Some things cannot be easily checked like the state of the battery unlike in iPhones which show battery health and even that might not be that reliable.
    Manufacturers often provide USSD codes for checking such things (for eg. just typing ##6485## in the dialer in a Xiaomi phone reveals battery health labeled good or bad under the tag MB_06). These are OEM specific and you can easily find them online.

    Good post! It might also be helpful to list some code-names for LineageOS supported devices that are available 2nd hand. When I tried last year, it was exceedingly difficult to find a cheap device that's also properly supported. (Nothing below $100 with direct support.)
    Corporate dumps new models every week, fragmenting the community.

    busy Check if the phone is carrier locked or not.

    How do you do that without testing the SIM?

    busy Some things cannot be easily checked like the state of the battery unlike in iPhones which show battery health and even that might not be that reliable.

    All that can be done as far as I know is comparing the reported mAh to the original spec. You can view it on Android too, here a free tool (also on F-Droid): https://github.com/darshan-/Battery-Indicator-Free
    That number is just an estimate, though. (But good enough to see if it's completely trashed, or not.)

    • busy replied to this.

          arvid How do you do that without testing the SIM?

          The same site as mentioned above(imei24.com). There ought to be other sites as well(needs research).
          Not sure how it all works altogether since most of the phones we have here are unlocked ootb but still a thing to be aware of.

          arvid All that can be done as far as I know is comparing the reported mAh to the original spec. You can view it on Android too, here a free tool (also on F-Droid): https://github.com/darshan-/Battery-Indicator-Free
          That number is just an estimate though. (But good enough to see if it's completely trashed, or not.)

          I'm not familiar with this but by the looks of it, it would take a lot longer(installing the app, letting it run in the background for a while so it can calculate and gauge it's health). I assume one wouldn't have that much of time on their hands in such scenarios. Not in denial of other methods but the OEM provided would for eg. state battery health as good if above 80%. Newer updates show the battery health in percentage as well, again it is OEM specific, differs from models and even android version it runs. This method is much quick and hassle-free.

                I'm a bit wary of giving IMEIs to 3rd parties, as they're unique. Might not matter on TorBB with a random location. Also wonder where they get their data from. I'd first try asking the carrier you use, as they will see it anyway. Apparently some vendors allow *#7465625# for checking.
                Leaking IMEIs via installed apps is also a consideration, so getting rid of Google is a must.

                busy I'm not familiar with this but by the looks of it, it would take a lot longer(installing the app, letting it run in the background for a while so it can calculate and gauge it's health).

                You don't need to wait if the battery reports current capacity. I think that's what you meant with the iPhone. You can access this either natively or via apps. All that matters is that it was fully charged at least once recently.
                You can view what is accessible directly in the docs: https://developer.android.com/reference/android/os/BatteryManager
                Apps can try to guesstimate what is really available on the respective API level, but as far as I know, batteries in general vary wildly. I'd only look for major deviations of spec capacity. For comparison: My 5y old phone has 76%, the 3y old laptop has a wear level of 27%, so 73% (without ever being actively used, always on AC).

                    7 months later

                    arvid
                    I've seen the agents who come to collect and test your phone value, when you exchange phone on amazon or flipkart, use an app like this, or literally this app most times, to guage the phone value -

                    PhoneCash -Sell Your Old Phone - https://play.google.com/store/apps/details?id=yaantra.phoneCash.app

                    This app takes around 5-10 mins for the whole test from my experience, and checks a whole bunch of things automatically and reports what's broken. If anything is, then the value goes down.
                    Maybe one can use this to test the device

                    Likely has spyware as with any app on the store as usual, but the utility seems nice enough

                      The name reminds me of the Eurotrash 'flip4new'. When I got rid of the phone slavery contract (Extremely common in Europe: 24/36+ months forced contract periods, for a stupid phone you ultimately pay more for, than if you'd just buy it outright.), and switched to prepaid Android/LOS 5+ years ago, I tried. They ask you if the device is SIM-locked, scratched etc. and gave me a 'preview' of 90 abusetokens (which is already a joke for a perfectly functioning 1000 EUR device without scratches).

                      You go out of your way to find a physical post office, pay the insane bus ticket cost, send it to them.

                      A while later you get an e-mail with always the same exact story stating 'their technicians have evaluated the device and are willing to pay you 5 bucks for it'. Seriously. I demanded they return the thing to me and sold it on ebay for a more typical price. Which is terrible in itself, as ebay has absolutely insane fees. But better than getting less than a kebab for the thing. Bus fare to the city and back is almost 10 abusetokens, a kebab is 7-8 now (was at least 4-5 or even 3 then though, pre-UA/COVID), offering 5 is an insult.

                      You can test the entire hardware yourself too - there was an open source app which lets you look at all the sensors. I forgot the name, but you can probably find it. For testing, you'd want to give it all permissions it can get, so might be worth the effort of avoiding a store app, before they leech everything. Or at least re-flash before you install it. But Android has infinite ways of abuse, and I sure as heck don't know how to 'fix' them all. So I just avoid it altogether.
                      Correlations are the new oil, and everything that can be collected, will be collected.

                      7 days later

                      I just found something else, if the phone you're trying to buy is a Xiaomi one, you can try dialining -

                      ##3646633##

                      to enter into "Engineering Mode". Other OEMs have other codes for this mode, look it up for your specific device brand of interest.
                      This also has a bunch of tests which may be useful as far as I can see

                      8 days later
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