01. Connect a phone
Install the ApiSIM gateway on a dedicated Android phone, pair it with a one-time code and pick the business SIM. Keep it powered and online; the dashboard shows when it is not.
Android first · your SIM, your number
API access
to your own phone.
For agents and automation.
Give your AI agents, CRM and scripts the business phone your customers already know. Send and receive SMS, place and answer calls, record with consent and get transcripts, all through one API, with honest delivery states.
No carrier registration paperwork · No rented numbers · 14 days free, one line, no card
↗ messages.incomingReply from +1 650 ··· 6621 · 2s ago
9:41
apisim
Business line · SIM 2
● Connected to your workspace
Messages
Voice calls
Recordings
agent → send_message“Hi Alex, want help getting started?”
Built for AI agents and automations Your existing Android phone and SIM Signed webhooks and replayable events EU hosting · opt-in recording
How it works
A phone in a drawer becomes
an endpoint your software can trust.
02. Connect your software
Create an API key. Send messages and start calls with idempotent requests. Replies, delivery states and call events come back through signed webhooks or a replayable event stream.
03. Keep the conversation
Calls can carry browser or AI audio and be recorded with consent. Transcripts arrive after the call. Only conversations you start or scope are synced, never a personal history.
Built for builders
A real phone.
A familiar API.
Pair once. Choose the line. Make the request.
Every action has an ID and an outcome you can follow: queued, accepted, sent, delivered, failed or uncertain. Never a silent retry.
POST https://api.apisim.app/v1/messages
Authorization: Bearer $APISIM_KEY
Idempotency-Key: followup-1042
{
"line_id": "your_business_line",
"to": "+15555550101",
"body": "Hi Alex, can I help you get started?"
}
// 202 Accepted
{ "id": "op_…", "state": "queued" }
// later, via webhook
{ "type": "messages.incoming", "data": { "body": "Yes please!" } }Honest by design
What it is, and what it is not.
Right-sized volume
A phone and SIM comfortably handle tens to a few hundred conversations a day. Follow your carrier’s fair-use rules. For spam-scale bulk sending, this is the wrong tool.
Calling depends on the carrier
Software audio on calls uses your carrier’s conference feature, including over Wi-Fi Calling. We verify every line before enabling calling, and we say so when it is not supported.
Your data, your rules
Recording is off until you turn it on and confirm you have consent. Recordings and transcripts are stored privately in the EU and deleted on your retention schedule.
Simple pricing
One price per connected line.
From $29 per line a month, yearly plans save two months. Recording and transcription are optional prepaid credits. Start free for 14 days with one line, no card required.