Rate limits

To keep the platform fast and reliable for everyone, the SIP Caller REST API limits the number of requests that each API key can make.

Limits

Each API key can make up to 20 requests per second, on average.

The limit applies to each API key separately. All requests count towards the limit, including the ones that fail.

Requesting a higher limit

If your integration needs a higher limit, contact us and explain your use case: what your integration does, how many requests it sends, and how they're distributed over time. We'll review it and help you find the best solution, which can include increasing the limit for your account.

Exceeding the limit

When the limit is exceeded, the API returns a 429 Too Many Requests error, with a Retry-After header indicating the number of seconds to wait before sending more requests:

HTTP/1.1 429 Too Many Requests
Retry-After: 5

{
  "type": "https://tools.ietf.org/html/rfc6585#section-4",
  "title": "One or more errors occurred.",
  "status": 429,
  "detail": "Too many requests. Retry after 5 seconds.",
  "instance": "/v1/accounts/ACCOUNT_ID/campaigns",
  "traceId": "0HN6QKQ1B2F3G:00000004"
}

Best practices

• Honor the Retry-After header. When you get a 429 error, wait at least the indicated number of seconds before retrying.
• Use bulk endpoints. Most operations accept many records in a single request. For example, add hundreds of numbers to a campaign in one Add numbers request, instead of one request per number, or upload a CSV file.
• Use webhooks instead of polling. Instead of checking for changes every few seconds, subscribe to webhooks to be notified when campaigns change state or calls end.
• Use larger pages. When reading long lists, request pages of a few hundred records instead of small pages. See Pagination.
• Spread out batch jobs. If a job sends many requests, add a short delay between them, instead of sending them all at once.