Software
The phone shipped with Android 2.3, as the first device to ship with the updated OS. On 19 December 2011, Google released Android 4.0 (Ice Cream Sandwich) for the Nexus S. The automatic update was suspended, allegedly due to poor battery performance. The UMTS/GSM variants was among the first to receive Android 4.0.4 in March 2012. The Nexus S 4G, I9020A, D720 and M200, while taking longer than the GSM variant, received the Android 4.0.4 update. Several devices, such as the Samsung Galaxy S II, have or will receive updates before these variants.
On 27 June 2012 at the Google I/O conference, it was announced that the Nexus S would be one of the first devices to receive an upgrade to Android 4.1 Jelly Bean, along with the Motorola Xoom and Galaxy Nexus, began on 26 July 2012.
On October 2012, the Jelly Bean 4.1.2 OTA update was released.
On 13 November 2012, it was announced that the Nexus S would not be updated to Android 4.2 Jelly Bean. It's still supported by independent developers, though, and Android 4.2.2-based alternative software can be installed.
Read more about this topic: Nexus Two