SMSVerifier API supports up to 10 simultaneous SMS retrieval requests per API key by default, with options to increase limits upon request.
Overview of simultaneous SMS retrieval requests
When integrating SMS verification via the SMSVerifier API, developers often need to retrieve one-time passwords (OTPs) or verification codes from multiple virtual phone numbers concurrently. This capability is essential for high-volume automation, parallel account registrations, or multi-service verification workflows.
Simultaneous SMS retrieval requests refer to multiple API calls made at the same time to fetch SMS messages or OTPs. Managing these requests efficiently requires understanding the API’s concurrency limits and rate-limiting policies.
Concurrency limits help maintain service stability, preventing overloads that could reduce SMS delivery speed or accuracy.
Default concurrency limits on SMSVerifier API
SMSVerifier enforces a default maximum of 10 simultaneous SMS retrieval requests per API key. This means that at any moment, your integration can have up to 10 active requests fetching SMS messages concurrently.
This limit applies globally per API key and is independent of the target service (e.g. WhatsApp, Google, Telegram). Whether you are retrieving OTPs from one or multiple services, the combined simultaneous requests count toward this limit.
Handling rate limiting and errors
When the maximum number of simultaneous SMS retrieval requests is exceeded, the SMSVerifier API responds with an HTTP 429 status indicating "Too Many Requests". This is a protective mechanism to prevent server overload and ensure fair usage among all customers.
To handle this gracefully, your application should implement error detection and recovery strategies:
- Detect HTTP 429 responses and pause new retrieval attempts temporarily.
- Use exponential backoff delays before retrying requests.
- Queue new SMS retrieval requests until current requests complete.
Ignoring rate limits can cause request failures and delays in receiving OTPs, disrupting your verification workflow.
Best practices for efficient integration
To optimize your SMS retrieval process while respecting concurrency limits, follow these recommendations:
Implement request queuing
Maintain a queue of SMS retrieval requests and dispatch only a limited number concurrently.
Use exponential backoff
On HTTP 429 errors, delay retries progressively to reduce load pressure.
Cache received messages
Avoid redundant API calls by caching OTPs and only polling when necessary.
Monitor your request concurrency in real time to dynamically adjust polling rates and avoid hitting limits.
Increasing your simultaneous request limit
For high-volume users or enterprise applications, SMSVerifier offers the option to raise the concurrency limit beyond 10 simultaneous requests.
To request an increase:
- Contact SMSVerifier support via your dashboard or email.
- Describe your use case, expected volume, and performance requirements.
- Provide details on your current API usage and integration.
After evaluation, SMSVerifier can grant higher concurrency quotas to accommodate your needs, ensuring smooth SMS delivery and retrieval.
Increased concurrency limits may require additional verification to protect service quality and prevent abuse.
Frequently asked questions
What is the maximum number of simultaneous SMS retrieval requests allowed by SMSVerifier API?
Can I increase the limit for simultaneous requests?
What happens if I exceed the maximum number of simultaneous requests?
How can I optimize my application to handle SMS retrieval efficiently?
Does SMSVerifier API have global rate limits beyond simultaneous request limits?
Are simultaneous requests counted across all services or per service?
Where can I find more details about SMSVerifier API limits and usage?
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