Teams building voice usually buy speech-to-text from one vendor, text-to-speech from another, understanding from a third, and write the orchestration themselves.
Every seam is a place for latency and context to leak. The agent forgets what the caller said two turns ago because the transcript and the intent live in different systems.
Vollo puts all four in one platform so the context survives the whole turn, and so a developer can ship a voice agent without becoming an integrator first.