This should explain tje update / release process.
http://developer.sonymobile.com/2011/12/07/ice-cream-sandwich-from-source-code-release-to-software-u...
The Certification and approval phase: Making sure the software and hardware is compliant
A phone comes with parts and software working with a number of different technologies, such as Bluetooth, Wi-Fi, modem and so on. To use these technologies, we have to certify that the new software is compliant with these technology standards. We therefore need to certify a new software release for all of these different technologies due to operator community requirements (GCF ,PTCRB , CCF) and Intellectual Property Rights (IPRs), if we have modified the software module related to such technology.
To a great extent, we try to get global certifications, but in many cases specific countries demand specific tests. For a global, worldwide product, we need local certifications approvals in up to 80 countries. For all these external certifications we are either allowed to test ourselves, and submit evidence that we passed, or we can get external test houses, such as Cetecom, to perform the tests.
Besides the operator and IPR certifications, we must externally comply with certifications for regulatory requirements. For example, we must show evidence that we comply with spurious emissions, SAR, EMC, as well as other environmental and health compliances. But when it comes to software upgrades for existing phone models, not all of the regulatory certifications are needed as they have already been performed once.
On top of this, Sony Ericsson is doing internal self certifications in areas we have identified as extra important to deliver the highest possible quality.
All certifications are based on each phone model, and even if a phone model has been certified with a previous software release, the parts which have been changed must be recertified if we are doing a new software release. So if we, for example, have made changes to the Wi-Fi module in an existing phone model, we need to recertify it. When we are working with a new Android release, such as Ice Cream Sandwich, all the affected areas must be recertified.
Another example is if the Bluetooth stack is changed. Then we have to recertify the Bluetooth part of the new software release. There are many apps that needs to be recertified for each of our phones, if they are changed in a new Android software release, for example Bluetooth, MMS, Wi-Fi, HDMI, DLNA and Adobe FLASH. Besides this, we rerun the Android Compatibility Test Suite (CTS) to make sure that we are compliant.
Contrary to what people may think, it is not the Bring up phase, but the Certification and approval phase that is the most time consuming process when it comes to getting a new software release out on our phones. This is one of the major tasks that are legally required from us as phone manufacturer, but is a task that the custom ROM community doesn’t have to take into consideration. Furthermore, by putting all this efforts into testing and certification, we ensure that quality and conformance is at a top level, in benefit for all consumers worldwide.
Additional approvals might be needed
In some cases, the new and complete software release has to be approved to be used in all the different networks that our phones should work in. Many operators also want to customise the software according to their requirements, which in turn are based on their market, network, differentiation and business model. We implement all of these customisations and create a variety of software packages and releases for each operator.
When all of this is done, we are ready to roll out the software release variants as software upgrades to operators and consumers around the world. The software upgrade can then be downloaded and installed either in the operator’s own update tool (if they have one), from Sony Ericsson’s PC Companion tool, or by over the air updates (FOTA – Firmware Over the Air).
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It should be pointed out that this summary of all the activities and phases is somewhat simplified and is meant to provide a general picture of what we do from the release of the first Ice Cream Sandwich source code, until it is released to our consumers. From Sony Ericsson, we hope it has shed some of light on the work being done for the software upgrades.
If you have any question on this topic, feel free to drop us a line below. We will try to respond as soon as possible. For general software announcements and product information, please check the Sony Ericsson Product Blogregularly.
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from SONY they say end of March then April now May when you see at Sony support you found that the the update realesed in 04/24/2013 but nothing (http://www.sonymobile.com/fr/software/phones/xperia-p/) can any one answer about this what about you Sony can you give is the SI roll out my SI is ( 1261-6560 ) 
