gtbs: Add Generic Telephone Bearer Service support

Tag: #feature
Bug: 159786353
Bug: 213412267
Sponsor: jpawlowski@
Test: build
Change-Id: Iecd56b91ce59f6b014878691fe4c6fae826b73f9
5 files changed
tree: 30e3592857dcbd3d44e33d0ac6f29216554875b1
  1. framework/
  2. service/