How to migrate from MessageFlow to Vonage

MessageFlow is a cross-channel messaging platform from Polish CPaaS company Vercom S.A., exposing email, SMS, RCS, Viber and WhatsApp through a single REST API. Vonage is a communications-API provider (part of Ericsson) covering SMS, MMS, voice and multichannel messaging over REST. On the messaging.dev Score, MessageFlow rates 59/100 and Vonage 89/100 — treat that as a data point about breadth and maturity, not an endorsement, and read on for what actually changes at the code level.

What changes when you move

Channels you gain: MMS, Facebook Messenger and Voice are available on Vonage but not on MessageFlow. Channel you lose: Email — MessageFlow sends email (and exposes SMTP alongside REST), while Vonage is REST-only and does not offer an email channel. SMS, RCS, WhatsApp and Viber exist on both platforms; neither offers Telegram or Apple Messages for Business.

Compliance: both providers are GDPR, ISO 27001 and SOC 2 aligned, so you lose no certification. Vonage additionally lists HIPAA alignment.

Data residency: MessageFlow stores data on EU (EEA) servers only, with no US option and no region choice. Vonage offers both EU and US servers, a data-residency choice, plus APAC and Australia regions.

Pricing model: this is a structural change. MessageFlow bills monthly subscription tiers priced by contact count (Starter from €69/month) with bundled volumes and overages, plus a Mix & Match plan from €465/month. Vonage is pay-as-you-go per message/minute with volume discounts (roughly $0.0072 per US SMS segment, plus carrier fees). Rebuild your cost model around per-message pricing rather than monthly bundles.

Free credit: MessageFlow gives a 30-day trial of 100 SMS + 100 emails; Vonage gives €2 of trial credit.

SDKs and docs: MessageFlow lists no official SDKs; Vonage ships Node.js, Python, PHP, Java, C#, Ruby and Kotlin SDKs, and its documentation rates as high quality versus MessageFlow’s medium. Both provide a sandbox test environment.

How the request format differs

MessageFlow (source):

curl -X POST https://api.messageflow.com/v2.1/sms \
  -H "Authorization: YOUR_API_KEY" \
  -H "Application-Key: YOUR_APPLICATION_KEY" \
  -H "Content-Type: application/json" \
  -d '{"sender":"YourCompany","message":"Hello world!","phoneNumbers":["+48111222333"]}'

Vonage (target):

curl -X POST 'https://rest.nexmo.com/sms/json' \
  -d 'api_key=YOUR_API_KEY' \
  -d 'api_secret=YOUR_API_SECRET' \
  -d 'from=Vonage' \
  -d 'to=15551234567' \
  -d 'text=Hello from Vonage'

Endpoint: you move from https://api.messageflow.com/v2.1/sms to https://rest.nexmo.com/sms/json (legacy SMS API) or https://api.nexmo.com/v1/messages (Messages API).

Authentication: MessageFlow uses two HTTP headers — Authorization (a 128-character key) and Application-Key. Vonage’s SMS API instead passes api_key + api_secret as request parameters; the Messages API uses JWT auth. The credential concept changes from paired header keys to a key/secret pair (or a signed JWT).

Payload mapping: MessageFlow sends a JSON body; Vonage’s SMS API takes form-encoded fields. Map sender → from, message → text, and the phoneNumbers array → a single to value. Note the structural shift: MessageFlow accepts an array of recipients in one JSON call, whereas the Vonage SMS example targets one recipient per to field.

Migration checklist

1. Create a Vonage account and generate your API key and secret (and a JWT/application for the Messages API if you need WhatsApp, RCS, Viber, MMS or Messenger).
2. Map each request field: sender→from, message→text, phoneNumbers[]→to.
3. Re-point your sending code to the new endpoint and switch from JSON headers to form params (or adopt a Vonage SDK).
4. Re-test against Vonage’s sandbox before sending live traffic — it has one.
5. Update delivery-receipt webhooks and callbacks to Vonage’s format and register your callback URLs.
6. Run both providers in parallel and reconcile delivery reports.
7. Cut over once parity holds, then decommission MessageFlow.

For a from-scratch walkthrough, see how to start with Vonage, and for the full side-by-side, see the MessageFlow vs Vonage comparison.

Watch out for

• Email disappears. MessageFlow’s email channel (and SMTP) has no equivalent on Vonage; keep or find a separate email provider.
• Pricing shifts to pay-as-you-go. Monthly bundled volumes become per-message billing — re-forecast spend accordingly.
• Smaller trial. Vonage’s €2 credit is a thinner runway than MessageFlow’s 100 SMS + 100 emails.
• Two APIs, two auth models. The quick curl uses the legacy SMS API (key/secret); multichannel sending runs through the Messages API with JWT auth, so plan for both.