How to migrate from Telesign to Vonage

Telesign is a digital identity and programmable communications platform offering SMS, RCS, voice, WhatsApp, Viber, and email APIs. Vonage, part of Ericsson, is a communications-API platform covering SMS, voice, video, and messaging. On the messaging.dev Score, Telesign rates 70/100 and Vonage 89/100; this guide covers what actually changes when you move your sending code from one to the other.

What you gain and lose

Channels. Both platforms carry SMS, RCS, WhatsApp, Viber, and voice, so those integrations map over directly. Moving to Vonage adds MMS and Facebook Messenger. The one channel you lose is email — Telesign exposes an email API, Vonage does not, so any transactional email flows need a separate provider after cutover. Neither platform offers Telegram or Apple Messages for Business.

Compliance. Identical on both: GDPR, ISO 27001, SOC 2, and HIPAA aligned, so no certification is lost in the move.

Data residency. Both run US and EU servers. Vonage adds an explicit data-residency region choice plus APAC and Australia regions; Telesign offers US/EU without a documented residency-choice control.

Pricing and credit. Telesign uses pay-as-you-go per-message/per-transaction pricing with public rates not transparently listed. Vonage is also pay-as-you-go (with volume discounts) but publishes rates — approximately $0.0072 per US SMS segment plus carrier fees. Both include free developer credit; Vonage specifies €2, while Telesign’s amount is unpublished.

Tooling. Docs quality is high on both, and both are REST. Vonage ships the same six SDK languages as Telesign (C#, Java, Node.js, PHP, Python, Ruby) plus Kotlin, and — unlike Telesign — provides a sandbox test environment. Vonage also publishes a 99.95% uptime SLA where Telesign lists none. One point in Telesign’s favor: it reports 230 countries covered versus Vonage’s 200.

For a fuller side-by-side, see Telesign vs Vonage.

How the request format differs

Telesign’s quickstart call:

curl -X POST https://rest-ww.telesign.com/v1/messaging \
  -u "CUSTOMER_ID:API_KEY" \
  -H "Content-Type: application/x-www-form-urlencoded" \
  -d "phone_number=15551212&message=Your message here.&message_type=ARN"

Vonage’s quickstart call:

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'

Three things change:

• Endpoint. You POST to https://rest-ww.telesign.com/v1/messaging on Telesign; on Vonage the legacy SMS API is https://rest.nexmo.com/sms/json (or the newer Messages API at https://api.nexmo.com/v1/messages).
• Authentication. Telesign uses HTTP Basic auth — Customer ID as username, API key as password. Vonage’s SMS API takes api_key and api_secret as body parameters instead; its Messages API uses JWT.
• Payload. The recipient field phone_number becomes to, and the body field message becomes text. Telesign’s curl carries no sender and a message_type=ARN flag; Vonage requires a from sender ID and has no message_type equivalent.

Migration checklist

1. Create a Vonage account (self-onboarding) and copy your API key and secret from the dashboard; the €2 trial credit lets you test immediately. See how to start with Vonage.
2. Map the fields: phone_number → to, message → text, add a from sender, and drop message_type.
3. Swap auth from HTTP Basic to api_key/api_secret body params — or JWT if you adopt the Messages API.
4. Re-point your sending code at the new base URL, or switch to an official SDK (Kotlin is now available if you need it).
5. Re-test against Vonage’s sandbox before sending live traffic — Telesign had none, so this is a new option worth using.
6. Update your delivery-receipt webhooks and callbacks to the Vonage payload format.
7. Run both providers in parallel, compare delivery, then cut over.

Watch out for

• Email disappears. Vonage has no email API; migrate those flows to a separate provider.
• Country coverage. Vonage lists 200 countries versus Telesign’s 230 — verify your key destinations are covered.
• Sender ID required. Vonage expects a from value; requests modeled on Telesign’s sender-less call will need one added.
• Two APIs, two auth models. Decide up front between the legacy SMS API (key/secret) and the Messages API (JWT); they differ in both endpoint and authentication.