Im asking myself how to best set up Vapi for my mostly european clients. In specific i have two questions: Can I route my twilio number through another edge location e.g. ireland? - will that improve latency (processing might still take place in the US)? How big is the impact on latency using TTS, STT and/or LLM in different regions (and maybe Vapi converstaion websocket resides also in the US)? Thanks for the help upfront!

Hey Filippo, Currently, Vapi’s servers are based in the US, so being closer to the US generally results in better latency. For telephony, however, the impact is minimal. If you choose a server in Europe, the user-to-Twilio latency may decrease, but the Twilio-to-Vapi latency will increase, making the overall difference negligible. Although it may provide a slightly better experience for the user. For voice calls, this usually doesn’t have a significant effect. However, for TTS, STT, or LLM interactions, it’s recommended to be based in the US, as server-to-server communication will be faster and most providers have readily available infrastructure there. You may experiment with both if in you can, Vapi provide latency report with calls so you can easily compare.

Thank you for your answer. That helps a lot. This make sense. Since I have read it on otehr messages, is there a plan for VAPI to offer processing in the EU?

Not that I am aware of, but the team will ofc plan to explain in EU as well, I'll forward this to the product team so they can take a look, but we currently don't have a timeline for it.

@Filippo You can improve some of the audio latency issues but using a service like Cloudonix as an in-between. Cloudonix maintains audio processing infrastructure in the EU, which ensures your inbound/outbound audio is processed locally. Them, it uses its internal network to route the audio in the shortest path to its destination - in this case, VAPI in the US.