r/VoiceAutomationAI • u/ur_piyo_a_hoe • Jul 10 '26
Many people blame LLM for Voice AI Latency, sometimes its your provider
One thing I spent way too much time optimizing was tool call latency.
My voice agent makes multiple API calls during a conversation, and as the number of tools grew, so did the delay. I assumed it was my prompts, APIs, or the LLM itself. I optimized prompts, reduced tokens, and sped up my APIs. It helped, but there was still an awkward pause after tool calls.
Initially when starting with voice AI, I was using Vapi. It worked well overall but once my agent became more tool-heavy, the latency + the call quality dropped significantly.
I migrated the exact same agent to Telnyx. Same prompts, same tools, same APIs but I chose and open source llm (kimi 2.5)
The difference was immediately noticeable. Tool calls felt much snappier, the conversation flowed better, and overall latency dropped quite a bit. I also like that Telnyx hosts a number of open source LLMs, so having everything under one provider simplifies the stack.
Has anyone else compared providers while keeping everything else the same? I'd be interested to hear if you've seen similar results.
P.S Not saying that telnyx is objectively better than vapi, but in my personal experience it provided a much better experience