However, the March security update has been released nearly a month ago by Nokia, and I haven't seen it yet. Nokia support are blaming UK carriers for not approving the update. Is this the case with iD mobile?
If so, this is preventing a bug in a major feature (for me) of my phone. Can anyone from iD support confirm what is going on?
Best answer by DeliriousMetro
Google will release an PDK development kit for the device manufacturer and if the integrated update passes the certification requirements (these are defined through each API level requirements on the Android Developer website) and the chipset manufacturer has provided their updated hardware libraries and is a supported device (some features may require a newer instruction set which may not be present on older chipsets) then the device manufacturer will conduct internal testing to ensure the software is reliable and the carrier will have to perform their own internal testing and if this is successful with their implementations (e.g. any additional apps/firmware support for features like VoLTE), then they will give off the green light for Technical Acceptance (TA) for the device manufacturer to allow the upgrades present on the device for that carrier through specific carrier CDA/CSC firmware.
Therefore, it is a waiting game for Nokia to sort out pushing firmware's onto their OTA servers and ensuring the carriers have submitted their technical acceptance from their own testing. It is known for some carriers not use CSC/CDA carrier customisation's and to use generic firmware with generic modems (I think this is the case with iD Mobile for the Xperia devices, for now.). The specialised firmware will also include any specialised modem features such as Wi-Fi Calling and VoLTE implementations, though this is determined by the carrier if they're willing to support your device.
Seeing how Nokia do not have a CSC/CDA carrier customised firmware, this is not the case. They're simply determining firmware based on country regions instead of carriers so this is all generic firmware from their own internal conducting team. They probably use different model numbers (like 001 for UK and 002 for US and 003 for China, as the frequencies used for 4G LTE and the technology is different, for example, some chipsets may only support certain bands in the EU and these wont work in China, the technology of 4G is also different between countries, such as, FDD (Frequency Division Duplex) and TDD (Time Divison Duplex), we in the UK and EU use FDD-LTE but people in China use TDD), subtle differences in firmware's occur due to this. Radio intensities will also need to measured to ensure they're legal (but this is probably done in the initial release of the firmware and not any further).
TL;DR: It's the internal testing that Nokia has to perform to allow Technical Acceptance in the UK region for it to be pushed onto the OTA servers for devices to update. In this case, it is not the carriers job but Nokia's as they are releasing the firmware without customisation from the carriers.
Any customisation's from the carrier are performed through provisioning from their side (without specific firmware implementation) to enable features like VoLTE/Wi-Fi Calling it seems for the Nokia's.
Any security patches from Google will be released as it is named; patches. They're small binary files which tell what files to modify in the system partition (e.g. any changed system dependent libraries). There is honestly not much need for internal testing etc.
The update is rolled in phases of bursts, so older serial numbers are more likely to get the update first and the phases increase in capacity in order to identify any unknown bugs before giving the firmware to the general population.
Take a look here and you can see that other people in the UK region (SIM-free, Vodafone, O2, EE, 3) are in the same boat.
They do seem to update certain regions faster like South Africa (I assume technical acceptance criteria is lower for their regions).
If you wish to go the unofficial route, you can place the update.zip firmware if you have the TA-1012 handset onto your sdcard and flash it in recovery but this carries a huge risk on you. It's not recommended by iD or people without experience.
This is how Android firmware is built for many devices from my experience as a previous Android developer. In most cases, the manufacturer will stop releasing updates as the chipset may be too old to support the latest features, the device will no longer pass Google's specific certification or it's an End Of Life product or r&d dev team simply find its not viable to support. (This is an entirely different case that happens towards the end of life for that device)