Synthflow is a no-code platform for building AI voice agents, and unlike most of its peers it already has a native payment story. Its Stripe integration lets agents charge callers during conversations, reconcile transactions automatically, and keep billing in sync, all without writing code. Synthflow also markets PCI-compliant handling with credit-card redaction across its SOC 2, HIPAA, PCI DSS, and GDPR certified infrastructure.
So this guide is not "Synthflow can't take payments." It can, through Stripe. This guide covers what the native Stripe integration does, where it stops, and when teams reach for Shuttle as the payment layer instead of, or alongside, the native option.
The short version: if you run on Stripe and that is all you need, the native Synthflow integration may be enough. If you need more than one payment gateway, per-client routing for an agency, or true PCI scope reduction via in-call card capture, that is where Shuttle fits.
What the Native Synthflow + Stripe Integration Covers
The native integration is built on Stripe. From the documentation, it lets you:
Charge callers during conversations inside automated agent workflows, white-labelled to your brand
Reconcile transactions automatically and keep billing data synced across your organisation
Run agency and subaccount billing by connecting a Stripe account to create custom plans, included minutes, and usage-based overage
Synthflow also pairs with native telephony providers including Twilio, Telnyx, RingCentral, and Vonage, and applies selective redaction to sensitive data such as card numbers within its certified infrastructure.
For a business that runs entirely on Stripe, that covers the common cases, including the debt-collection and outbound use cases Synthflow promotes.
Where the Native Integration Stops
Two limits matter most, and they hit agencies hardest.
It is Stripe-only. The native integration connects to Stripe. If you use Adyen, Worldpay, Checkout.com, or any other gateway, or an end client mandates a specific PSP, the native path does not reach it. This is the sharpest constraint for Synthflow's agency and subaccount model: an agency running agents for many clients cannot route each client to that client's own gateway on a Stripe-only integration.
Redaction is not the same as keeping card data out of scope. Marketing PCI-compliant infrastructure with credit-card redaction is real, but redaction means card data has already entered the pipeline and is being scrubbed. A payment layer that captures the card in an isolated environment, so the digits never enter the agent flow or your recordings at all, is a stronger PCI posture. The documentation does not detail an in-call keypad (DTMF) capture path that keeps card data out of the agent entirely.
How Shuttle Fits
Shuttle is a PCI DSS Level 1 certified Service Provider that acts as a payment layer across your channels, including Synthflow agents. You can use it instead of the native integration when its limits bite, or alongside it.
**Multi-PSP routing.** Shuttle connects to 30+ payment gateways including Stripe, Adyen, Worldpay, Checkout.com, Braintree, Square, and Mollie. Route by client, region, currency, card type, or failover, all through one integration. For Synthflow agencies, each client can use its own gateway.
True in-call DTMF capture. Shuttle takes control of the DTMF channel, captures keypad digits in its certified environment, and masks the tones so they never reach Synthflow or your recordings. The agent's voice pauses during entry and resumes on the result, so card data stays out of the pipeline rather than being redacted after the fact.
Payment links too. Shuttle also sends hosted payment links by SMS across any supported gateway, so you keep the link option without being tied to Stripe.
How It Works with Shuttle
Your Synthflow agent runs the conversation and reaches the payment step.
A workflow action triggers Shuttle to create a payment session with the amount, currency, and gateway configuration.
The customer pays either by keypad (Shuttle captures and masks the DTMF) or by a secure link Shuttle sends.
Shuttle processes the payment through your configured gateway inside its certified environment.
The result returns to your workflow, and the agent confirms the payment.
Card data never enters Synthflow or your recordings, so your business stays at SAQ-A.
When to Use Which
Native Synthflow + Stripe: you are Stripe-only, charging callers through Stripe is enough, and you do not need per-client gateway routing.
Shuttle: you need more than one gateway, you run an agency that routes clients to different PSPs, a client mandates a specific gateway, or you want in-call keypad capture that keeps card data fully out of scope.
FAQ
Can Synthflow agents take payments natively? Yes. Synthflow has a native Stripe integration that lets agents charge callers during conversations, with automatic reconciliation and agency-friendly billing.
**Does the native integration support gateways other than Stripe?** No. It is Stripe-only. For Adyen, Worldpay, Checkout.com, or per-client routing, you need a multi-PSP payment layer such as Shuttle, which connects to 30+ gateways.
Can an agency route each client to its own gateway? Not on the Stripe-only native integration. Shuttle supports per-client gateway configuration through a single integration.
**What does Shuttle cost?** $0.20 per transaction, with no setup fees or monthly minimums.
Related Reading
Retell AI Payments: PCI-compliant payment capture for Retell AI voice agents
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ElevenLabs Payments: native Stripe vs multi-PSP for ElevenLabs agents
How AI Voice Agents Take PCI-Compliant Payments: the technical architecture for secure payment capture during AI voice calls
What Are Voice Payments? The Complete Guide: IVR, agent-assisted, and AI voice payment models compared
Add Multi-PSP Payments to Your Synthflow Agents
Shuttle is Twilio's official payment partner and a PCI DSS Level 1 certified Service Provider. If your Synthflow agents have outgrown Stripe-only payments, or you run an agency that needs per-client gateway routing:
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