I have recently bought a german number in twilio (hosted in Ireland). With this number, I can make outbound calls in Vapi. I have assigned an assistant to this number for inbound calls, however, when I call the number, it says that the number is vacant. I have another german number (hosted in the US), and this number works perfectly fine for inbound calls.

It sounds more like a Twilio issue. @Henryk faced the same issue: inbound calls were not working properly, and he contacted support. They fixed it.

I just contacted the Twilio support, thanks a lot! 🙂