Turn your own Android phone into an SMS gateway for your application. One API request sends a sign-in code, an order update or an alert through your SIM, and signed webhooks tell your systems what happened next.
Not open to the public yet. Ask for access and we will contact you.
POST https://sms-api.nxsvs.com/v1/messages/send
x-api-key: <your API key>
Idempotency-Key: <a unique ID for this request>
Content-Type: application/json
{
"from": "<your connected phone number>",
"to": "<recipient's phone number>",
"content": "<your message>"
}Or failed / expired. "Delivered" appears where the recipient's network reports delivery.
NXSVS SMS sits between your application and your phone. It checks your key, queues the message and tracks it; your phone does the sending, over your own mobile operator.
And back: sent, delivered, failed and expired messages, replies, and your phone going offline or online reach your application as signed webhooks.
The controls a team needs to run messaging from its own software.
Your endpoint hears about each change as it happens, signed with HMAC-SHA256 so you can prove it came from NXSVS SMS.
Give each application its own key, starting nx_, instead of sharing your account key. Keys are sent in the x-api-key header.
Set send_at to queue a message up to 20 days ahead.
Send an Idempotency-Key header, and a retried request never sends the same message twice.
Texts your phone receives reach your account and your webhook.
Get an event when a phone drops offline, and another when it comes back.
On a dual-SIM phone, choose which SIM a message goes from.
Attach a request_id to trace each message back to your own records. Include attachment URLs to send MMS.
Versioned under /v1, authenticated with one header, and answered with the queued message straight away. Full guides and an interactive API reference open with the service.
| pending | Accepted and queued. |
|---|---|
| sending | Your phone has picked it up. |
| sent | Your phone handed it to the mobile network. |
| delivered | The recipient's network reported delivery. Not every network reports it. |
| failed | It could not be sent. |
| expired | It was not sent in time. |
POST https://sms-api.nxsvs.com/v1/messages/send
x-api-key: <your API key>
Idempotency-Key: <a unique ID for this request>
Content-Type: application/json
{
"from": "<your connected phone number>",
"to": "<recipient's phone number>",
"content": "<your message>",
"send_at": "<optional: an ISO time up to 20 days ahead>",
"request_id": "<optional: your own reference>"
}200 OK
{
"status": "success",
"message": "message added to queue",
"data": {
"id": "<message id>",
"owner": "<your phone number>",
"contact": "<recipient's phone number>",
"status": "pending"
}
}X-Webhook-Event-Id: <unique event ID>
X-Webhook-Timestamp: <timestamp>
X-Webhook-Signature: v1=<hex HMAC-SHA256 of
timestamp + "." + body>
Recompute the signature with your webhook's secret,
compare it, and use the event ID to skip repeats.What NXSVS SMS does to keep your keys, events and messages under your control, and one honest note on what SMS itself cannot do.
A separate key per application, so one leaked key does not expose the whole account.
Verify the HMAC-SHA256 signature on every delivery, and use the timestamp and event ID to reject replays and repeats.
Messages, phones and keys are looked up within the account that owns them.
Idempotency keys make a network retry safe: the same request never sends twice.
Message content can be encrypted between your application and your phone. The SMS itself still travels as ordinary text on the mobile network.
A phone joins your account by scanning a QR code from your own dashboard.
NXSVS SMS sends through a phone you own. That phone has to stay ready to send.
Plans are set up by our team while NXSVS SMS is in early access. SMS charges are separate: your mobile operator bills them under your SIM's plan.
Texts go out through your own SIM, so your mobile operator charges for them under your plan. Your NXSVS SMS plan covers the platform: the account, the API, webhooks and the queue.
Short, straight answers. Anything else, ask us.
Not yet. It is in early access: ask for access and we will contact you when your account is ready.
No. Messages are sent from your phone's own number. There is no alphanumeric sender ID.
Your mobile operator, under your SIM's plan. Your NXSVS SMS plan covers the platform: the account, the API, webhooks and the queue.
Your webhook receives phone.heartbeat.offline, and phone.heartbeat.online when it is back. A message your phone cannot send in time is marked expired, and you are told by webhook.
You will know when your phone has sent it. "Delivered" appears when the recipient's network reports delivery, and not every network does.
No. It sends from an ordinary SIM, which is not a bulk route. It is made for the messages your own customers expect from you: codes, updates and alerts.
Tell us what you want to send, and we will get back to you with access and a quote.