We're trying to determine a way to send DTMF into the call. As we understand, It's only possible by using this Vonage API -> https://developer.nexmo.com/api/voice?theme=dark#play-dtmf. But initiating a call using TokBox API -> "v2/project/{this.ApiKey}/dial" does not provide call "leg UUID" in response. There are only these properties in response:
{ "id": UUID, "connectionId": UUID, "streamId": UUID }
Is there any way to get leg UUID from TokBox/Nexmo API call response or by any other way?
A few weeks later we figured that out. The trick is in calling on your own number from TokBox, then using webhook; we're getting call details and calling to 3rd party from Nexmo by adding a new member to a conference. TokBox -> SIP-conference.
This hack is undocumented and strips a lack of feature.