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Add card-on-file payments to a Deepgram Voice Agent by call transfer. This works like a hosted web checkout, over the phone: when the order is confirmed, your bridge creates a Checkout Session and transfers the live call to a Ringup payment line, the caller pays there, and the call optionally returns to your agent. Ringup recognizes the caller, charges their saved card, settles it against the order, and texts a receipt. Your server reconciles from a webhook. If the model is new to you, read Call transfer first. Deepgram has no telephony of its own: your bridge (typically Twilio) owns the call leg, so the transfer happens on the bridge, and setup is code in that bridge. This page is end to end: setup, the call, the return, and what happens after payment.

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How the pieces map to Deepgram

Ringup pieceOn Deepgram
create_checkoutAn HTTP POST your bridge makes when the order is confirmed
The transfer targetThe transfer_to SIP URI the Checkout Session returns
The transferA <Dial><Sip> on your bridge’s telephony (Twilio) to the Ringup SIP URI
The resultA checkout.completed webhook to your server

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Prerequisites

  • A running Deepgram Voice Agent behind your own audio bridge (Twilio media streams or similar).
  • Your bridge’s telephony account (the number the call comes in on).
  • A Ringup account and API key. Test mode works out of the box on a shared sandbox. See Testing.

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Step 1: Create a Checkout Session in your bridge

When the agent signals the order is confirmed (for example via a Deepgram function call your bridge handles), POST to Ringup’s create_checkout endpoint with your Ringup API key. There is no platform tool to register; this is a plain HTTP call from your bridge. 
POST https://api.ringup.dev/v1/checkouts
Authorization: Bearer <YOUR_RINGUP_KEY>
Content-Type: application/json

{
  "amount_cents": 2500,
  "line_items": [{ "name": "Large pepperoni", "quantity": 1, "amount_cents": 2500 }], // optional
  "order_id": "sq_abc",                              // optional: settle against an existing order
  "return_to": "sip:your-bridge@your-twilio-number", // optional: transfer the caller back after payment
  "success_message": "You are all set, your order will be ready shortly."  // optional (if no return_to)
}
Response (the Checkout Session): 
{
  "id": "cs_x9f2",                                   // Checkout Session id; the correlation token
  "payment_required": "required",                    // "required" | "optional" | "none"
  "transfer_to": "sip:cs_x9f2@transfer.ringup.dev"   // where to transfer; embeds the id
}
If payment_required is none, do not transfer: finish the call normally. Otherwise transfer.

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Step 2: Transfer on your bridge

Have your agent speak one bridge line (an InjectAgentMessage such as “One moment, connecting you to secure payment”), then transfer the caller on your telephony. On Twilio, redirect the call to TwiML that dials the Ringup SIP URI, carrying the Checkout Session id: 
<Response>
  <Dial>
    <Sip>sip:cs_x9f2@transfer.ringup.dev?X-Session-Id=cs_x9f2</Sip>
  </Dial>
</Response>
Because your bridge controls the telephony, the header path is reliable: the URI parameter reaches the Ringup line, which matches it to the Checkout Session.

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Step 3: The return, and the result (the webhook)

Ringup answers the transferred call, recognizes the Caller, charges the saved Card, and texts a receipt. A first-time caller with no saved card is texted a secure pay link instead. Then the call ends one of three ways, from what you passed in Step 1:
  • return_to set: Ringup <Dial>s the caller back to your bridge with the outcome in SIP headers (X-Payment-Status, X-Confirmation), so your agent resumes and closes the call.
  • success_message / failure_message set (no return_to): Ringup reads your line and ends.
  • Neither: Ringup reads a short default and ends. The receipt is the proof.
A return_to that cannot connect falls back to reading your success_message (or the default), so a failed return never strands the caller. Either way, your server reconciles from a webhook: 
{
  "id": "evt_9f2",
  "type": "checkout.completed",         // or "checkout.failed"
  "data": {
    "checkout_id": "cs_x9f2",
    "payment_id": "pay_abc",
    "amount_cents": 2500,
    "order_id": "sq_abc",               // echoed back
    "confirmation": "2PJJZY",
    "caller": "+14155551234",
    "card": { "brand": "VISA", "last_4": "5858" }
  }
}
Match on the order_id you passed, store the payment_id, and flip your order to paid. See Webhooks for the full catalog, statuses, signature verification, and idempotency.

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Validation status

Because your bridge owns the telephony, the transfer is standard <Dial><Sip> on your provider. Ringup’s hosted transfer endpoint is rolling out; confirm access in your Ringup dashboard before relying on this in production. The recognition, charge, receipt, and webhook behavior is the same payment path Ringup runs everywhere.