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 a secure handoff that keeps card data out of the agent, 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 your systems. 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 hands the call to a secure, isolated capture, so the digits never enter the agent flow or your recordings at all, is a stronger PCI posture. The documentation does not detail a secure 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. Shuttle has no native integration with Synthflow. Instead, your application code invokes Shuttle's Twilio-based payment setup, and at the point of payment the call is handed to a secure capture via Twilio Pay. You can use it instead of the native integration when its limits bite, or alongside it. To use the secure voice capture, you must be a Twilio customer.
Multi-PSP routing. Shuttle connects to 30+ payment gateways including Stripe, Adyen, Worldpay, and Checkout.com. Set which provider handles each payment type, and set amount and currency limits on when each method is offered, all through one integration. Switching gateways is configuration, not re-integration, though saved cards stay with the gateway that stored them. For Synthflow agencies, each client can use its own gateway. A few gateways (Braintree, for example) do not work for voice capture but do work for payment links.
Secure in-call card capture. At the point of payment, the call is handed to a secure PCI DSS Level 1 capture via Twilio Pay. The customer enters their card on the keypad, and Twilio Pay captures the digits and passes them to Shuttle's PCI DSS Level 1 environment, so they never reach Synthflow or your recordings. Card data stays out of the pipeline rather than being redacted after the fact.
Payment links too. Payment links are the turnkey path. Shuttle sends hosted payment links by SMS or email across any supported gateway, including mid-call, so you keep the link option without being tied to Stripe.
One honest caveat: the secure capture at the point of payment is live now via Twilio Pay. Shuttle handles the payment segment of the call, not the whole conversation. Returning the caller to the same Synthflow agent after payment works today: you program the return route in your Twilio flow and pass a conversation ID, so the agent picks the call back up with full context. Your team builds the agent-side orchestration that triggers the handoff, and you can validate it against Shuttle's sandbox gateway and demo app first. Shuttle works with Twilio today, and any carrier coming soon.
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 during the secure Twilio Pay capture (Twilio Pay captures the digits and passes them to Shuttle's PCI DSS Level 1 environment) 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 PCI scope is heavily reduced: merchants complete SAQ-A and platforms complete SAQ-D. To return the caller to the same Synthflow agent afterwards, program the return route in your Twilio flow and pass a conversation ID so the conversation resumes with context.
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 a secure in-call keypad capture that keeps card data out of the agent. The secure voice capture requires you to be a Twilio customer.
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. Switching gateways is configuration, not re-integration, though saved cards stay with the gateway that stored them.
Does Shuttle have a native Synthflow integration? No. Shuttle has no native integration with Synthflow. The handoff is API-driven: your application code triggers Shuttle's Twilio-based payment setup, and at the point of payment the call is handed to a secure PCI DSS Level 1 capture via Twilio Pay.
Does this require Twilio? Yes, for the secure in-call capture. The capture runs over Twilio Pay today, so you must be a Twilio customer. Shuttle works with Twilio today, and any carrier coming soon.
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? For voice, $49 per live instance per month, plus from $0.20 per transaction, falling with volume, billed through your Twilio account. See pricing. For technical detail, see the Shuttle docs: Twilio setup, payment links, and security and PCI.
Related Reading
Retell AI Payments: PCI-compliant payment capture for Retell AI voice agents
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Bland AI Payments: secure payment capture for Bland AI phone agents
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 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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