Telephony providers
You can use third party telephony providers in Tovie DialogStudio. There are multiple telephony providers in the market that you can use. This article provides a couple of examples and specific connection instructions.
Vonage
Vonage is a provider of cloud solutions for business communications.
Zadarma
Zadarma is a cloud PABX with quick configuration and a wide choice of virtual numbers.
Register an account in Zadarma and create a new SIP connection in Tovie DialogStudio. When configuring a SIP connection, use details from the Settings → SIP connection in Zadarma. Also disable the Call without a country code option in the Settings → My profile → Calls tab.