Places an outbound call (POST /v1/calls); resolves the created call UUID.
Hangs up a call (PUT /v1/calls/:uuid { action: 'hangup' }) by UUID.
Sends DTMF digits on a call (PUT /v1/calls/:uuid/dtmf) by UUID.
Transfers a call (PUT /v1/calls/:uuid { action: 'transfer', destination }) by UUID.
The minimal Vonage Voice API surface RealVonageBindings drives — the calls we need:
createCall(outbound dial),hangupCall(end),transferCall(PUT /v1/calls/:uuidtransfer), andsendDtmf(PUT /v1/calls/:uuid/dtmf). A production wiring implements this over a@vonage/server-sdkVoiceclient; tests inject a fake.