Errors

Error response format, HTTP status codes, error codes, pagination, and troubleshooting for the KaiCalls API.

Error Response Format

All errors return a consistent JSON structure with a machine-readable code and a human-readable message:

json

{
  "error": {
    "code": "unauthorized",
    "message": "Invalid or expired API key"
  }
}

HTTP Status Codes

Status	Meaning
`200`	Success
`201`	Resource created
`400`	Bad request — missing or invalid parameters
`401`	Unauthorized — invalid, expired, or revoked API key
`402`	Payment required — x402 payment needed (signup endpoint only)
`403`	Forbidden — key lacks required scope or business access
`404`	Not found — resource does not exist or is not accessible
`429`	Rate limited — too many requests
`500`	Internal server error

Error Codes

The error.code field in every error response will be one of these values:

Code	HTTP Status	Description
`unauthorized`	`401`	API key is missing, invalid, expired, or revoked
`forbidden`	`403`	Key lacks the required scope or business access
`not_found`	`404`	Resource not found
`bad_request`	`400`	Missing required parameters
`invalid_request`	`400`	Parameter validation failed
`vapi_error`	`500`	Error communicating with voice AI provider
`call_failed`	`500`	Outbound call could not be placed
`payment_required`	`402`	x402 payment header required
`content_blocked`	`400`	SMS content failed compliance check
`number_opted_out`	`400`	Recipient has opted out of SMS
`number_on_dnc`	`400`	Number is on Do Not Call list
`tcpa_violation`	`400`	TCPA compliance violation
`rate_limit_exceeded`	`429`	Too many requests
`sms_send_failed`	`500`	SMS delivery failed
`internal_error`	`500`	Unexpected server error

Pagination

All list endpoints support cursor-based pagination using these query parameters:

?after=<ISO timestamp>

Cursor: pass the created_at value of the last item in the previous page.

?limit=<number>

Results per page. Maximum varies by endpoint (typically 100).

has_more

Every list response includes a has_more: boolean field. When true, fetch the next page using after.

bash

# First page
curl "https://kaicalls.com/api/v1/calls?limit=25" \
  -H "Authorization: Bearer kc_live_..."

# Next page (use created_at of last item)
curl "https://kaicalls.com/api/v1/calls?limit=25&after=2026-04-17T12:00:00Z" \
  -H "Authorization: Bearer kc_live_..."

Troubleshooting

Common issues and how to resolve them:

1401 on every request

Check that the key starts with kc_live_ or kc_test_ and is passed in the Authorization: Bearer header. Verify the key has not been revoked or expired.

2403 Forbidden

Your key may be scoped to a different business, or missing the required scope. Check the key's scopes in the dashboard.

3Empty results

Your key may be scoped to a business with no data for that resource. Check business_id scoping.

4Rate limited on signup

Wait 1 hour. The /v1/signup endpoint is limited to 5 requests per IP per hour.

See the Authentication guide for key setup, or return to the full API reference.