According to the GFX Benchmark site, the Sony D5103 is reportedly going to be released with Android 4.4.2 under the hood, powered by a quad-core Snapdragon 400 processor with the Adreno 330 handling graphics. The device will carry a 4.8 inch screen with resolution of 720 x 1280. Back and front facing cameras weigh in at 8MP and 1.3MP (or higher) respectively.
Unlike Sony's high-end models, the Xperia G is not expected to be waterproof or dustproof. Perhaps its inclusion on the POSTEL site indicates that a release is coming soon.
Sony D5103 appears on Indonesia's POSTEL website
1. The Sony D5103 is listed on Indonesia's POSTEL site
2. Image allegedly of the Sony Xperia G
source: GSMInsider via Engadget