Only enable voicemail transcription on android O and later

Bug: 65648343
Test: updated unit tests (already submitted in previous cl)
PiperOrigin-RevId: 169280819
Change-Id: I5950087765ffd038c31b872c6468951472980407
2 files changed
tree: 3dfc9527855b2df0228369dd9af84a005b0b2009
  1. assets/
  2. java/
  3. Android.mk
  4. AndroidManifest.xml
  5. CONTRIBUTING
  6. LICENSE