The biggest problem with the Android platform has been how slowly many phone makers release the latest version of the OS for their older models. It's also not unusual for them to never do so. (A company may not want to spend resources on phones they no longer sell; or, they and the carrier for a particular model may not agree on when to provide an update.)
If you own such a neglected phone, and don't want to buy a new one, then your best shot is installing unofficial Android firmware on it.
The following is a primer on what you should know about the process of installing unauthorized Android firmware. Each phone can have its own unique steps for doing this, so you should follow instructions for your specific model.
1. INSTALL AT YOUR OWN RISK
Installing unofficial OS firmware on your phone will likely render whatever warranty from its maker you have on it null and void.
Thoroughly read the installation instructions for your specific phone model and then follow them carefully, taking time and patience. Though the odds of bricking your phone -- rendering it inoperable because of something going wrong during the install process -- is fairly low, it can happen and especially so if you rush through things.
Be aware that some features on your phone running its current version of Android may no longer be available after you successfully install a custom Android firmware. Other features could be buggy or have quirks.
2. TWO CHOICES: CYANOGENMOD OR MIUI
In the unofficial Android firmware development community, there are two major choices: CyanogenMod and MIUI. Both are built on the Android source code officially released by Google, and their latest versions are based on Android 2.3 (codenamed Gingerbread). As of this writing, the volunteer development teams of both projects are working to get new versions built on Android 4.0 ("Ice Cream Sandwich").
What's the difference between the two? CyanogenMod sticks with the basic, default components of Android that come with its source code release; its UI is "clean," devoid of unnecessary extras. MIUI completely overhauls the stock Android UI with one that resembles that of Apple's iOS.
If not, there is still a chance that somebody may be working on a port for your specific phone; search its model name in the official community forums for CyanogenMod or MIUI to see if there is such an on-going effort. (An excellent source to check is Android Forums.) But know that some or several features of your phone may not work if you install such an experimental, work-in-progress build of CyanogenMod or MIUI that is not officially sanctioned by that OS's community.
3. ROOT YOUR PHONE
Before you can start to do anything to your phone, you'll need to root it, which means basically to unlock the security settings put in place in the OS to prevent it from being altered. Check out GingerBreak to help you conveniently root your phone.
Unfortunately, this app tool might not work on more recent Android phones. This guide provides a list of instructions for rooting several specific phone models.
4. BACK UP YOUR CURRENT FIRMWARE AND PHONE DATA
You really want to do this if you need to re-install your phone's original firmware and data later (e.g., something goes wrong when you install the unofficial Android firmware; you decide you don't like CyanogenMod or MIUI; or, you need to reactivate your phone with its carrier, something which you cannot do when running either of these unofficial OSs on it).
The easiest way to do a back-up is to install ClockworkMod ROM Manager on your phone. Run this app, and select "Reboot into Recovery" from its menu. This downloads and installs a recovery image profile for your phone, restarts it, and loads a plain-looking text menu, where you can select the back-up process.
After the copy of your phone's firmware and data is made, you can move it to a computer for safekeeping. Connect your phone by USB cable to your computer, then simply drag-and-drop the backup's folder (it's on your phone's SD card under the folder "clockworkmod") from your phone's SD card to the latter device.
5. PREPARE GOOGLE'S DEFAULT ANDROID APPS FOR INSTALLATION
If you're installing CyanogenMod: Unless you want to keep your to-be-upgraded phone clean of Google apps, you'll need to install them separately. CyanogenMod does not include the standard Google apps that typically come pre-installed on an Android phone. So you'll have to download a ZIP file that contains the installation packages for apps such as Google Search and, most importantly, the Android Market. Put this ZIP in the main root directory of your phone's SD card.
6. INSTALL THE CUSTOM ANDROID FIRMWARE
This is the big deal. Download the CyanogenMod or MIUI firmware designed specifically for your phone model, which comes in the form of a ZIP package, and save it in the root directory of your phone's SD card.
Once again, run the ClockworkMod ROM Manager app, and select "Reboot into Recovery." After your phone restarts into the ClockworkMod Recovery tool, you may need to wipe out its data and cache, and format its "/system" directory -- this depends on whether you are installing CyanogenMod or MIUI, so you should refer to the instructions that specifically are for your phone.
Next, you select the ZIP file of the custom Android firmware you placed in the root directory of your phone's SD card, and start the upgrade process. It normally takes less than two minutes. If you're upgrading to CyanogenMod: Don't reboot your phone just yet... repeat the above step for the ZIP file containing the Google Android apps.
You return to the main menu of the ClockworkMod Recovery tool and select to reboot your phone. After about 2 minutes, it should boot and then run on the custom Android firmware.
7. ENJOY YOUR NEW ANDROID PHONE!
Besides updating your phone to a more recent version of Android, CyanogenMod and MIUI can also give it new features and tools, which include better power management, Wi-Fi tethering, stronger security settings, and broader personal customization of the UI. Many users report their phones run faster with one of these unofficial OSs than with the version of Android that came originally installed on it.
Wen is a freelance writer. He can be reached at email@example.com.