Microsoft has updated the Windows Device Recovery Tool firmware delivery for the Lumia 550. Firmware version 15503.21007 is now available through it, which is a bump from the 15461.48007 version it shipped with. In addition, the firmware update now mirrors the one Microsoft rolled out for the Lumia 950 and Lumia 950 XL at the end of 2015.
The update is not yet available over-the-air (OTA), so Lumia 550 users will be required to use the Windows Device Recovery Tool for PC in order to wipe and update to this latest version. A changelog for the update is also not available, so it's not known which features or fixes may get applied with the it. Unless you are facing certain issues with your phone, it might be better to wait for the OTA update, which won't require a wipe.
The OS version remains the same at 10586.29 with the firmware update, but today may see the roll out of build 10586.71 for the Lumia 550 and other supported devices via the Windows Insider Program. Microsoft had previously announced that Cumulative and firmware updates for the Lumia 950 and 950 XL won't start rolling out until February. But if you don't want to wait, users can opt into the Windows Insider Program to get the latest Windows 10 Mobile builds.
If you have updated your Lumia 550 to this new firmware, let us know in the comments if you have spotted any changes or notable fixes. Microsoft's newest budget Lumia 550 can be availed for as low as £59.99, unlocked in the UK or for $139 in the US.