Programmable SMS API

Two-way SMS and MMS from one REST call.

Send and receive SMS and MMS from dedicated business numbers over a single REST API. Delivery receipts arrive as webhooks, TCPA opt-outs are handled automatically, and every message also lands in the VanceTel softphone shared inbox in real time.

Two-way SMS & MMSDelivery receiptsAuto opt-out handlingShared softphone inbox

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Send an SMS

curl https://api.netexem.com/v1/messages \
  -H "Authorization: Bearer $NETEXEM_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "from": "+15551234567",
    "to": "+15557654321",
    "body": "Your appointment is confirmed for 2pm — reply STOP to opt out."
  }'

One POST sends a text — and it lands in the softphone too.

Send a message

POST to /v1/messages. Get a typed message back.

Authenticate with a bearer token, pass a from-number you own, a destination and a body. VanceTel queues the message, returns its id, and tracks status from there.

Send an SMS

curl https://api.netexem.com/v1/messages \
  -H "Authorization: Bearer $NETEXEM_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "from": "+15551234567",
    "to": "+15557654321",
    "body": "Your appointment is confirmed for 2pm — reply STOP to opt out."
  }'

Request — a single JSON body with from, to and body.

201 Created

{
  "id": "msg_3Jq8x2P0c1",
  "object": "message",
  "from": "+15551234567",
  "to": "+15557654321",
  "direction": "outbound",
  "status": "queued",
  "segments": 1,
  "createdAt": "2026-05-31T14:02:11Z"
}

Response — the message id is your handle for delivery receipts and threading.

Receive a reply

Inbound texts arrive as signed webhooks.

Subscribe your endpoint once. When someone texts your number, VanceTel posts a message.received event — the body, any media and a conversation id you can reply against.

message.received for inbound SMS and MMS
message.delivered, message.failed for DLR status
Every payload HMAC-SHA256 signed for verification

POST /your-webhook · message.received

{
  "type": "message.received",
  "data": {
    "id": "msg_9Lk2m7Qa4",
    "from": "+15557654321",
    "to": "+15551234567",
    "body": "Yes, see you at 2.",
    "media": [],
    "conversationId": "conv_5Tg1n",
    "createdAt": "2026-05-31T14:05:43Z"
  }
}
# X-Netexem-Signature: t=1748700343,v1=9f86d0818...
# Verify the HMAC-SHA256 signature, then 200 OK to acknowledge.

What the API does

Everything a business messaging stack needs.

Delivery receipts (DLR)

Subscribe to message status webhooks — queued, sent, delivered or failed — each event HMAC-SHA256 signed so your endpoint can trust it.

Opt-out compliance

STOP, START and HELP are intercepted and honored automatically. A blocked recipient is rejected before send, so you stay on the right side of TCPA.

Group SMS

Open a single conversation across multiple participants. Replies thread back into one group, addressable by a stable conversation id.

Templates with variables

Define reusable message templates with {{variables}}. Send with a payload of values and let the API render the final body for each recipient.

MMS & rich media

Attach images and files via secure upload URLs, add link previews, or drop in an in-message voice note. One API for SMS and MMS alike.

Lands in the softphone

Every API message also appears in the shared inbox in real time — on iPhone, iPad, Mac, Apple Vision Pro, desktop and web — so your team can reply by hand.

Compliance built in

TCPA opt-out, handled for you.

VanceTel intercepts STOP, START and HELP automatically and tracks every recipient’s opt-out state. A send to an opted-out number is rejected before it leaves — so consent management is part of the platform, not a feature you build and maintain yourself.

FAQ

SMS API questions, answered.

Want to see two-way SMS land in the softphone live? Book a walkthrough.

Book a demo

Is this an A2P 10DLC SMS API?

Yes. VanceTel sends application-to-person messages from dedicated business numbers registered for A2P 10DLC, so your traffic is carrier-compliant. You call one REST endpoint to send; VanceTel handles the brand and campaign registration plumbing behind your numbers.

How are opt-outs handled?

Automatically. VanceTel intercepts STOP, START and HELP keywords and manages each recipient’s opt-out state for you. A message to an opted-out number is rejected before it sends, and the opt-out is recorded — so TCPA compliance is built in rather than something you code by hand.

Do messages show in the app?

Yes. Every message you send or receive over the API also appears in the VanceTel softphone shared inbox in real time — across iPhone, iPad, Mac, Apple Vision Pro, desktop and web. Your software drives the conversation and your team can still reply by hand from a real app.

Can I send MMS and group messages?

Both. Attach images or files through secure upload URLs to send MMS, and open a single group conversation across multiple participants where replies thread back into one addressable thread. Link previews and in-message voice notes are supported too.

How do I know a message was delivered?

Subscribe to delivery-receipt (DLR) webhooks. VanceTel posts a status event — sent, delivered or failed — to your endpoint as the carrier reports it. Every webhook is HMAC-SHA256 signed so you can verify it came from VanceTel.

Ship programmable SMS this week.

One REST API for two-way SMS and MMS, delivery receipts and opt-out compliance — with every message in the VanceTel softphone your team already uses.

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