Programmable Voice, VoiceML

Move compatible Programmable Voice workloads without rewriting call logic.

VoiceML is VoiceTel's XML-based voice runtime for teams that already have voice markup, callbacks, recordings, conferences, queues, and API-driven call flows. Keep the interaction model; move the economics and support path to VoiceTel.

Build voice workflows on VoiceTel without paying retail markup on every layer of the call. Use API-driven calling, SIP access, recordings, conferences, streams, transcriptions, queues, and status callbacks on a platform built for telecom teams.

Start migration Compatibility matrix

VoiceML example

The markup stays readable, inspectable, and easy to test before cutover. A small inbound IVR — gather a digit, route to a queue, fall back to voicemail:

<?xml version="1.0" encoding="UTF-8"?>
<Response>
    <Say voice="Polly.Joanna">Welcome to Acme Support. Press 1 for billing, 2 for technical support.</Say>
    <Gather numDigits="1" action="/route" method="POST" timeout="6">
        <Say>You can also stay on the line to reach the next available agent.</Say>
    </Gather>
    <Dial timeout="20">
        <Queue>support</Queue>
    </Dial>
    <Record maxLength="120" transcribe="false" action="/voicemail" />
    <Say>Thanks. We'll follow up within one business day.</Say>
</Response>

Webhook signatures, parameter names, and verb behavior match Twilio's voice markup, so an existing handler at /route or /voicemail works unchanged once you point your application's host at voiceml.voicetel.com.

Compatible voice surface

  • Calls

    Create, fetch, update, list, and end calls using the supported voice-call lifecycle surface.

  • VoiceML call control

    Answer, route, record, gather, dial, queue, conference, redirect, stream, and transcribe calls using XML-based voice markup.

  • Recordings

    Start, pause, resume, stop, list, retrieve, and delete supported recordings.

  • Conferences and queues

    Use conference resources, participants, recordings, queue CRUD, and queue members where supported.

  • Streams, transcriptions, and SIP recording

    Start and inspect supported live media, transcription, and SIP recording resources with documented caveats.

  • Applications

    Save voice-only application defaults and resolve them from call creation where supported.

  • Signed webhooks

    Status, recording, gather, dial, conference, AMD, and action callbacks use signed webhook delivery for request verification.

  • Bring your own media vendors

    Use your preferred speech-to-text, text-to-speech, and recording storage providers; VoiceTel does not hide third-party provider costs inside vague platform claims.

What's different

  • Voice-focused compatibility — The compatible SDK surface is voice-focused. Messaging, number provisioning, pricing APIs, and other unrelated CPaaS products use native VoiceTel product APIs or portal workflows.
  • Unsupported payment verb — The payment verb is intentionally not implemented because PCI scope belongs in a fully certified payment flow.
  • Number provisioning path — DIDs are managed through VoiceTel number workflows, not through the compatible customer-facing voice API surface.

VoiceML FAQ

Can existing Twilio voice applications migrate?

Yes, when they stay within the supported VoiceML-compatible voice surface. Review the compatibility matrix before production cutover.

Which text-to-speech providers does VoiceTel support?

Supported text-to-speech integrations. Open-source engines run on VoiceTel infrastructure; cloud vendors are billed by you directly.

Which speech-to-text providers does VoiceTel support?

Bring your own speech-to-text provider and pay the vendor directly. Supported integrations:

How are rates displayed?

Current public rates are on the pricing page, with a calculator that applies volume-tier discounts. Your customer portal displays the same rates plus any account-specific contract pricing.

What's better

  • Line-item pricing. Every rate published on the pricing page. Speech, recording storage, and TTS billed by you directly to your chosen provider — VoiceTel does not mark up third parties.
  • Operating since 1999. 27 years in business — ISP origins, now full-stack carrier with engineers who read SIP traces, not qualification scripts.
  • No platform tax. Inbound messaging included. The published per-minute rate is what gets billed — no per-minute platform fee on top.
  • Honest compatibility. Every supported verb and attribute labelled in the compatibility matrix. No silent feature gaps mid-migration.