How to migrate from SMSAPI to Telnyx

SMSAPI is a Polish business-messaging platform (a brand of LINK Mobility Poland) that sends bulk SMS, MMS, RCS, WhatsApp and voice over a REST API. Telnyx is a licensed telecom carrier running a CPaaS platform for SMS, MMS, RCS, WhatsApp, voice and email over its own private global IP network. On the messaging.dev Score the two sit apart — SMSAPI at 44/100, Telnyx at 78/100 — so this guide walks through what actually changes at the API and compliance level when you switch.

What changes when you move

Channels. You keep every channel you use today: both providers support SMS, MMS, RCS, WhatsApp and voice. The one channel you gain is email, which Telnyx offers and SMSAPI does not. Neither supports Viber, Facebook Messenger, Telegram or Apple Messages for Business, so nothing changes there. Migrating costs you no channels.

Compliance and residency. Both are GDPR-compliant and ISO 27001 certified. Telnyx adds SOC 2 and HIPAA, which SMSAPI does not carry — relevant if you handle regulated US data. SMSAPI keeps all data in the EEA (two redundant data centers in Poland), with no region choice and no US servers. Telnyx runs both EU and US servers, lets you choose your data-residency region, and also covers Asia-Pacific and South America. You gain flexibility but lose the built-in guarantee that data never leaves the EEA — if EU-only residency is a hard requirement, configure Telnyx’s residency region explicitly.

Pricing and credit. SMSAPI bills prepaid pay-as-you-go credit with a minimum top-up around €30 and rates from ~€0.04 per SMS. Telnyx bills pay-as-you-go per message part (from $0.004 per outbound SMS part in the US, plus carrier fees) with volume discounts. Note the per-message-part model: long messages split into segments are billed per segment. SMSAPI gives free test SMS on signup; Telnyx has no free developer credit.

Tooling. Docs quality is high on both sides. SDK coverage overlaps on PHP, Python, Java and Go; Telnyx adds Node.js, Ruby and .NET, while SMSAPI’s JavaScript, C# and Bash helpers have close equivalents. Both expose REST; SMSAPI also offers SMTP (email-to-SMS) and Telnyx offers SMPP for high-volume binary connections. One difference to plan around: SMSAPI has a sandbox, Telnyx does not. For a dimension-by-dimension view, see the SMSAPI vs Telnyx comparison.

How the request format differs

Source (SMSAPI):

curl -X POST -H "Authorization: Bearer YOUR_API_TOKEN" "https://api.smsapi.com/sms.do?to=48500000000&from=SenderName&message=Hello+world&format=json"

Target (Telnyx):

curl -X POST https://api.telnyx.com/v2/messages \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -d '{
    "from": "+15551234567",
    "to": "+15559876543",
    "text": "Hello, world!"
  }'

Three things change. The endpoint moves from https://api.smsapi.com/sms.do to https://api.telnyx.com/v2/messages. Authentication stays a Bearer header in both — you swap SMSAPI’s OAuth 2.0 API token for a Telnyx API key, so the header shape is unchanged. The payload structure changes the most: SMSAPI passes fields as URL query parameters, while Telnyx expects a JSON body plus a Content-Type: application/json header. Field mapping: to stays to (but Telnyx wants E.164, e.g. +15559876543); from stays from (SMSAPI accepts an alphanumeric SenderName, Telnyx expects an E.164 sending number); and the message body renames from message to text. Drop the format=json parameter — JSON is native to Telnyx.

Migration checklist

1. Create a Telnyx account (self-onboarding) and generate an API key from the dashboard. The how to start with Telnyx guide covers the full setup.
2. Map your request fields: message → text, keep to/from but convert both to E.164, and move parameters from the query string into a JSON body.
3. Re-point your sending code to https://api.telnyx.com/v2/messages, add the Content-Type: application/json header, and swap the token for your Telnyx key.
4. Re-test. Telnyx has no sandbox, so test against the live endpoint with a small paid balance and a phone number you control.
5. Update delivery callbacks/webhooks to Telnyx’s delivery-report format and re-point the callback URLs.
6. Run both providers in parallel, comparing delivery receipts, before shifting all traffic.
7. Cut over and decommission your SMSAPI credentials.

Watch out for

• No sandbox on Telnyx — you will test against live, billable traffic.
• No free developer credit — SMSAPI’s free test SMS has no equivalent, so fund the account before testing.
• Per-message-part billing — multi-segment messages cost more than a flat per-SMS assumption.
• Sender format — alphanumeric sender IDs used with SMSAPI must become E.164 numbers on Telnyx, subject to destination rules.
• Data residency — you are moving to a US-headquartered carrier; if EU-only storage is mandatory, explicitly set Telnyx’s residency region.