notifications - Why does Google's Android C2DM service require android version later than 2.2? -

Google's cloud messaging, formerly known as C2DM Bata, was recently re-branded in GCM, to Android 2.2 up is required. Why is the question? What new features in 2.2 use C2DM, which do not support earlier versions?

C2 DM 2.2, and controlling the intentions of C2DM in robots with previous firmware Not specific services for