Plivo Voice API vs Voximplant

Plivo Voice API

US outbound at $0.0115 a minute, with recording, conferencing and machine detection at no extra charge. 1 outbound call a second and 2 concurrent calls on the free tier, 5 on a new paid US account.

Voximplant

Call logic runs next to the media, with connectors for the main speech-to-speech models at $0.004 a minute. Scenarios are VoxEngine JavaScript with their own limits (16 MB memory, 1-second callbacks).

Plivo Voice API

1. Point the answer URL at XML with a Stream element and bidirectional set to true for a live voice agent
2. Check concurrency before dialling out in bulk. Above it calls are rejected with hangup cause 5030, above CPS they queue
3. Don't rely on the status callback alone to learn a call ended. Poll the call if the webhook doesn't arrive
4. Validate webhook signatures before acting on call events

Voximplant

1. Upload a VoxEngine scenario and a rule first, then start it with StartScenarios and pass the number in script_custom_data
2. Use a service-account JWT rather than api_key in the URL
3. Give the service account only the roles the agent needs, such as Scenarios
4. Ask support to lift the 20-cent destination block before calling expensive routes