How does OmniDimension make its AI phone calls sound so natural, fast, and multilingual? Can a solo developer build something similar?

I’ve been testing OmniDimension, and I’m genuinely impressed with how it handles AI phone calls. It supports 100+ languages, has low-latency conversations, no-code setup, and the voice feels surprisingly natural.

I’m curious about the technical side of it.
What tech stack would you use to build something similar?

How do they keep conversations so responsive with such low delay?

Is it mainly a combination of STT + LLM + TTS, or is there more happening behind the scenes?

What would be the biggest challenge in building an AI calling platform at this level?

Could a solo developer realistically build an MVP, or would this require a full engineering team?