From my understanding and if I'm wrong plz correct me,nut Google stopped supporting the CDMAs.
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Google'ing this says you are correct, in a way. The core telephony APKs are carrier-provided as they are proprietary and must be signed with a different key than the AOSP build. Notice I said "carrier-provided" - hence, the blame lies with VZW. The Sprint version launched back on 4/22 and to my knowledge was running 4.0.4 at launch.
Google still provides the core OS, but the AOSP would have no voice/data functionality right out of the box.