Ask HN: Better Alternatives to Vapi (Voice Agents)?

I've been using Vapi for a few months now. However, I have the following concerns with it: - most importantly, integration with telecom services (e.g., Twilio) is not great especially for SIP trunking - UI is very unreliable and sometimes doesn't work - some features are incorrectly implemented / not documented correctly - Suboptimal customer support - Tool calls interrupt conversation - Conversation latency is far below competitors - No proper version control of agents (they have the history of the prompt, but that is also hard to read)

Anyone know of any services better than Vapi?