How Do You Migrate Client Accounts from Vapi, Retell, or Synthflow to a White-Label Platform?

To migrate from Vapi, Retell, or Synthflow to a white-label platform, run a parallel build first: inventory every client's numbers, billing, peak concurrency, and integrations, rebuild one pilot client on the new platform, cut over one account at a time, and keep the old setup live as a fallback until a full billing cycle passes cleanly. The migration itself is rarely the hard part. The risk is a client's phone line going quiet, or a client getting double-billed, because nobody wrote down how things were wired.

This checklist is written for agencies that already have paying clients on one of those platforms. It also helps if you're deciding whether the move is worth it. I won't characterize anyone's internals; where a claim about a competitor matters, check their own pricing and docs pages.

Should you migrate at all?

Only if the thing you're missing is on the reseller side. Developer-first voice platforms are built so you can assemble agents. A white-label platform is built so you can resell them: client sub-accounts, your branding on the dashboard, and your own billing relationship with each client. If your current setup works and your margins hold, migrating is a cost with no payoff.

The usual triggers are operational: you're stitching together client logins by hand, your clients can see a vendor's brand, or your per-minute costs make pricing awkward. What's the actual margin on reselling AI voice walks through that math. The NovaReps vs Vapi comparison lays out the structural differences, and there are equivalent pages for Retell and Synthflow.

What do you need to check on billing continuity?

Start with how each client is billed today, because the migration will touch it.

• Your invoice to the client versus your cost from the platform. Write down both per client. If your resale price was set around the old platform's cost structure, the new one may leave you more or less margin. Rework it before the move, not after. The agency pricing page shows how the new cost side is structured.
• Prepaid balances and credits on the old account. Check the terms on each vendor's page (Vapi, Retell, Synthflow) before assuming unused credit is refundable or transferable. Often it isn't, so time your cancellation after the balance is spent down.
• Overlap period. Plan for paying both platforms for roughly one billing cycle. Budget for it; don't let it surprise you.
• Annual commitments. If you're locked in, migrate clients gradually and let the old contract run out.

What about?

Don't assume it. NovaReps does not offer, and you should confirm the supported path with any platform, because it varies and the failure mode is a dead line.

Look at where each client's number lives. If it sits in a carrier account you control, the number may be repointable by changing the voice configuration at the carrier, without moving it anywhere. Twilio's porting documentation is a good reference for how carrier-level moves work and why they take time. If the number lives inside the old platform's own carrier arrangement, you may be stuck with forwarding from the old number or issuing a new one.

The practical options, in order of least client disruption:

1. Keep the number where it is and forward or repoint it to the new agent.
2. Issue a new number and update the client's website, Google Business Profile, and listings.
3. Forward the client's existing business line to a new number as a stopgap.

Per-tenant carrier isolation matters here: each client's calls run on their own carrier configuration, so changing one client's routing doesn't touch another's. For how carrier accounts work in a white-label setup, see do you need your own Twilio or Telnyx account. If your numbers have an unusual history, ask us directly what's supported before committing.

Will the new plan handle your concurrency?

Pull the real data, not a guess. From your current call logs, find the highest number of simultaneous calls per client and across your whole book. Then look at your worst day: a storm event for a roofer, a Monday morning for a dental office, or an outbound campaign launching at once.

Inbound peaks are usually modest per client. Outbound is where agencies get caught, because a campaign dialing in parallel can consume capacity that inbound clients also need. Compare your measured peaks against the new plan's limits, and check whether limits apply per account or are pooled. What a voice AI concurrency limit is and how it affects agency pricing explains how to read these numbers. If you can't find your peak in the old platform's logs, that gap is a finding in itself.

How do you avoid client-facing downtime?

Clients notice a missed call; they never notice a migration. So sequence it around calls:

1. Build the agent in parallel on the new platform with a test number. Do not touch the live line.
2. Test with real scenarios: a booking, a reschedule, an angry caller, a transfer to a human, an after-hours call.
3. Pick a low-volume window for the cutover, usually early morning or a weekend for most local businesses.
4. Repoint the number, then place several test calls immediately.
5. Keep the old agent live and the old route documented so you can roll back in minutes.
6. Watch the first few days of call logs for transcripts that look different from before.

Start with one friendly client as the pilot, not your largest account.

What breaks that people forget?

• Prompts transfer, voices don't. A prompt can usually be rewritten across platforms, but the voice and model behavior will differ. NovaReps has a dual voice engine and a choice of LLM and TTS providers, so re-audition voices and A/B the prompt instead of expecting it to sound identical.
• API keys. If you've been using your own LLM or TTS keys, check whether the new platform supports BYOK so you keep those relationships. What BYOK means for AI voice platforms covers the cost implications.
• Calendar connections. Google and Microsoft calendar bookings need re-authorizing for each client, and a test booking confirms the right calendar is writing.
• Webhooks and CRM hooks. Anything that listens for call events must be re-pointed. NovaReps sends webhook events, but your receiving endpoints and field mappings are yours to verify.
• Call history. Export transcripts, recordings, and logs from the old platform before you cancel. Check each vendor's docs for what's exportable, because deleted accounts rarely come back.
• Outbound compliance settings. Calling hours, consent records, and do-not-call lists don't carry over automatically. Rebuild them and confirm the outbound safety stack is configured per client before any dialing resumes.

How do you know you're ready?

If you can answer, for every client, where the number lives, what you charge versus pay, what the peak concurrency is, and what the rollback is, you're ready. If any of those is a blank, that's your next task. The agency readiness scorecard is a quick way to spot the gaps in your operation before you start moving accounts.