Example deployment: two-way CRM messaging

The business problem

One-way notifications tell customers things; the business value is in the answers — and without a return path, those answers land in a shared inbox nobody owns.

Recommended architecture

System trigger

Any CRM automation (Flow, Workflows, Deluge, Power Automate) or middleware. The key design decision is the metadata convention: every send carries contact_id and owner_id, and every reply comes back carrying them.

SendiMessage API request

curl -sS https://api.sendimessage.com/v1/send-message \
  -H "X-API-Key: $SENDIMESSAGE_KEY" \
  -H "X-API-Secret: $SENDIMESSAGE_SECRET" \
  -H "Content-Type: application/json" \
  -d '{
    "number": "+15555550123",
    "content": "Hi {{contact.first_name}}, your proposal is ready — any questions before we talk Thursday?",
    "status_callback": "https://your-endpoint.example.com/status?crm=your_crm&contact_id={{contact.id}}&owner_id=rep_789&workflow=proposal_follow_up"
  }'
# → {
#   "status": "QUEUED",
#   "message_handle": "4e828182-a640-483f-bfe9-17ffcaa51d48",
#   "to": "+14155550123",
#   "service": null,
#   "is_outbound": true,
#   "error_message": null,
#   "date_sent": null
# }

Channel behavior and SMS fallback

Conversations flow naturally on iMessage where supported; SMS fallback keeps every contact reachable. iMessage delivery is available on supported messaging lines and destinations. Recipients without iMessage receive SMS when fallback is configured — never assume universal iMessage availability.

Incoming replies

Replies are the product here: receive events carry your metadata back, middleware writes the reply to the record and notifies the owner. STOP handling updates consent state immediately. No ready-made connector is claimed for any CRM — the vendor guides show each system's trigger mechanism.

// "outbound" event → your your_crm endpoint
// Verify the SendiMessage-Signature header (t={timestamp},v1=HMAC-SHA256 of
// "{timestamp}.{raw body}", keyed with your webhook secret), then use
// GET /v2/messages/{message_handle} for authoritative state and match it to
// your contact_id in your_crm.

Messaging-line setup

One line per team or brand. Two-way volume grows with reply rates — usually the sign it's working.

Security checklist

• API key in server environment variables or a secrets manager — never in client code.
• Webhook signatures verified before any record is updated.
• Only the fields a message needs (phone, first name, reference id) leave your system.
• Reply text is untrusted input — sanitize before rendering inside CRM fields or notifications.

Run the full implementation readiness checklist →

Pricing and managed onboarding

Per active line plus usage in both directions. The pricing review covers reply-heavy workloads explicitly. Every line goes through managed onboarding: use-case review, test line, credentials delivered securely, and guided production activation.