SMS Delivery Tracking

Track the lifecycle of every outbound SMS: queued, sent, delivered, failed, and replied. Route delivery events to PostHog and your CRM for funnel measurement.

Twilio (Default)

Status callback webhook

When creating a message, include a StatusCallback URL:

const message = await client.messages.create({
  body: 'Your message',
  from: process.env.TWILIO_PHONE_NUMBER,
  to: '+1234567890',
  statusCallback: 'https://your-n8n-instance.com/webhook/twilio-sms-status'
});

Twilio POSTs to the callback URL as the message progresses through statuses:

| Status | Meaning | |--------|---------| | queued | Message accepted by Twilio | | sent | Message sent to carrier | | delivered | Carrier confirmed delivery to handset | | undelivered | Carrier rejected or could not deliver | | failed | Twilio could not send (bad number, blocked, etc.) |

Webhook payload fields:

• MessageSid — unique message ID
• MessageStatus — current status
• To — recipient number
• From — sender number
• ErrorCode — if failed/undelivered, the error code
• ErrorMessage — human-readable error description

Inbound reply webhook

Configure the phone number's SMS webhook URL:

curl -X POST "https://api.twilio.com/2010-04-01/Accounts/$TWILIO_ACCOUNT_SID/IncomingPhoneNumbers/$TWILIO_PHONE_NUMBER_SID.json" \
  --data-urlencode "SmsUrl=https://your-n8n-instance.com/webhook/twilio-sms-inbound" \
  -u "$TWILIO_ACCOUNT_SID:$TWILIO_AUTH_TOKEN"

Inbound webhook payload includes Body (message text), From (sender), To (your number), and NumMedia (attached media count).

n8n workflow for event routing

Build an n8n webhook node that receives Twilio status callbacks and:

1. Parses the MessageStatus field
2. Fires a PostHog event: sms_delivered, sms_failed, sms_replied
3. Updates the Attio contact record with last_sms_status and last_sms_date
4. If status is replied (inbound message), classify sentiment (positive/negative/neutral) using Claude and update Attio

Delivery rate calculation

Query PostHog for delivery rate:

delivered_count / (delivered_count + undelivered_count + failed_count) * 100

Target: >95% delivery rate. Below 90% indicates number quality issues or carrier filtering.

Salesmsg

Delivery tracking built into dashboard. Webhook integration available via Zapier or native webhooks (Settings > Webhooks). Events: message.delivered, message.failed, message.received. Route to n8n via webhook URL.

OpenPhone (Quo)

Delivery status visible in conversation threads. Webhook events available via API: configure webhook endpoints at Settings > Webhooks. Events include message.completed, message.failed, message.received.

Error Codes to Monitor

| Code | Provider | Meaning | Action | |------|----------|---------|--------| | 30001 | Twilio | Queue overflow | Reduce send rate | | 30003 | Twilio | Unreachable destination | Verify number, retry once after 24h | | 30004 | Twilio | Message blocked | Review content for spam triggers | | 30005 | Twilio | Unknown destination | Invalid number, remove from list | | 30006 | Twilio | Landline or unreachable | Mark as non-mobile, exclude from SMS | | 30007 | Twilio | Carrier content filtering | Rewrite message, avoid links/spam words | | 21610 | Twilio | Recipient opted out | Honor immediately, update suppression list |