Replacing Synthflow rebilling: three ways to bill your clients now.

What Synthflow's pricing plans used to do

It helps to list the jobs before replacing them. Synthflow's documentation for the removed feature, still published with a deprecation notice, describes a pricing plan as doing all of this:

• Charging a monthly fee through your connected Stripe account, in US dollars, euros, Canadian dollars or Australian dollars.
• Setting the maximum minutes and the maximum concurrent calls for the subaccount.
• Billing minutes beyond the allowance at an overage rate, if you enabled usage-based billing.
• Running a trial, with a number of trial days and a pool of trial minutes, then converting to paid.
• Copying agents and workflows into the subaccount when the plan was activated.
• Letting every teammate in a subaccount share one plan.

Since September 15, 2026 none of that runs. Minutes and concurrency moved to Limits & Capabilities. Everything involving money moved to you.

Option 1: stay on Synthflow, bill flat fees from your own Stripe

This is the least work, and it is what Synthflow's documentation tells affected agencies to do. Create a product and a subscription in your own Stripe account for each client, at the monthly price they already pay. In Synthflow, set each subaccount's included minutes to what that price covers and leave auto-overage off, so calls stop at the cap instead of running up minutes on your account.

• Good fit: a handful of clients on predictable volumes, or retainers where voice minutes are bundled.
• Trade-off: with auto-overage off, a client who hits the cap stops taking calls until you raise the limit by hand. With it on, Synthflow's documentation says the spend ceiling for that subaccount is removed and the extra minutes are billed to you.
• What you lose: clients no longer see their plan or usage inside the product.

Option 2: stay on Synthflow, build usage billing yourself

If you bill by the minute, you need the minutes. Synthflow's documentation gives three places to read them:

The billing cycle is yours now. Synthflow's documentation says to set minutes_used to 0 through the Subaccounts API when a client's invoice renews. Resetting the counter does not change the subaccount's minute limit and does not draw new minutes from your parent pool.

1. Read usage on a schedule or from the post-call webhook, and store it against the client.
2. Send it to your billing system. In Stripe that can be a metered price or an invoice line; any invoicing tool works.
3. Work out your margin there. Synthflow no longer calculates the difference between its rate and yours.
4. Reset minutes_used when the client's invoice renews.
5. Decide what happens at the cap for each client: stop calls, or allow auto-overage and invoice it.

• Good fit: agencies with a developer, or an automation builder already in the stack.
• Trade-off: you own the code, the reconciliation and the client's view of their usage. Synthflow's own page lists the exposure plainly: no automatic top-up, manual overage billing, no spend controls and manual margin reconciliation.

Option 3: move to a platform with rebilling built in

If billing clients from the platform was the reason you chose Synthflow, the direct replacement is a platform that still does it. Centerfy's White Label plan includes rebilling through your own Stripe account. From the Centerfy help centre:

• Your Stripe, your money. You connect your own Stripe account in the agency workspace. Funds land in your Stripe account, and Centerfy does not appear on your clients' invoices.
• Per-client pricing. Rebilling is switched on for each sub-account. You set a monthly plan price, per-usage rates, or both.
• More than voice minutes. Rates can be set for AI phone calls and phone calls per minute, SMS, WhatsApp and email per message, phone number rental per month, knowledge base sources and premium workflow actions.
• The charge is calculated for you. Centerfy calculates usage charges from the rates you configured, Stripe charges the client's payment method on file, and Centerfy records the transaction.
• Defaults and bulk edits. Default rebilling rates apply to new sub-accounts, and pricing can be updated across several sub-accounts at once.
• Usage in one place. The agency workspace shows usage across all sub-accounts. Each sub-account has a wallet balance and a list of billed usage, which are also available through the API.

What you pay Centerfy is the plan plus usage at the wholesale rates shown in your agency dashboard. What your clients pay is whatever you set.

• Good fit: agencies that want billing, usage and the agents in one place, and agencies that also sell SMS, chat and a CRM alongside voice.
• Trade-off: it is a move. Agents are rebuilt on Centerfy rather than imported, numbers are reconnected and workflows are repointed. See how a move works.
• Check before you commit: Synthflow caps minutes and concurrent calls for each subaccount. Centerfy's documented sub-account limits are AI agents, contacts, users and phone numbers. If a hard monthly minute cap per client is part of how you sell, ask Centerfy how to set that up before you move.

How to choose