@Benjamin Drury
I apologize for any confusion. Let me clarify:
Twilio's "Programmable Voice" is a service that allows you to make and receive phone calls programmatically using their API. It's the backbone for handling telephony operations like dialing out to phones, managing call flows, and more.
When you use VAPI's Text-to-Speech (TTS) service, you're using VAPI to convert text into spoken audio. However, if you want to deliver that audio to a phone call, you need a telephony service to handle the call itself – that's where Twilio's Programmable Voice comes in.
So, even if you're using VAPI for TTS, you're still using Twilio's Programmable Voice to manage the phone call part of the operation. That's why you see charges for both services: VAPI for the voice API (like TTS) and Twilio for the call handling (Programmable Voice).
If you need more detailed information on how these services are being used together in your specific case, or if you believe there might be an error in billing, please reach out to support for a thorough review of your account usage.