If you’re building an app with SMS verification, voice calling, or any communication feature, testing those flows reliably can be tricky. Using your own number or SIM cards isn’t scalable — and definitely not practical if you need to test internationally or simulate edge cases.
That’s where virtual phone numbers come in. They’re a simple, affordable, and developer-friendly way to test SMS, calls, and even VoIP features in your apps — without juggling physical SIMs or devices.
In this post, I’ll walk you through how to use virtual phone numbers for app testing, what to look for in a provider, and how they can improve your development workflow.
Why Use Virtual Numbers for Testing?
Here are some common scenarios where virtual phone numbers save the day:
- Testing SMS verification flows without spamming your personal phone.
- Checking international coverage without buying SIM cards from multiple countries.
- Debugging call routing or voicemail flows.
- Demoing chatbots, voice bots, or IVR systems safely.
- Running automated test scripts on your backend systems.
Essentially, they let you simulate real-world use cases — as many as you need — quickly and affordably.
How Do Virtual Phone Numbers Work?
A virtual number is just a phone number that lives in the cloud. You rent it from a provider and access it via a web dashboard, app, or API.
You can:
- Send and receive SMS.
- Make and receive calls.
- Record calls and view analytics.
- Switch between countries or number types (local, toll-free, etc.).
For developers, the API access is particularly valuable — you can script your tests and integrate them into CI/CD pipelines.
Steps to Use Virtual Numbers for Testing
Here’s how you can get started:
1️⃣ Choose a Virtual Number Provider
Pick a service like KrispCall that supports the countries and features you need.
2️⃣ Sign Up and Select Numbers
Create an account and rent virtual numbers for your target markets. You can usually pick between mobile, landline, toll-free, and even vanity numbers.
3️⃣ Set Up Your Testing Environment
Integrate their API or use the web dashboard to monitor incoming/outgoing SMS and calls.
4️⃣ Run Your Tests
- Simulate real user interactions:
- Send SMS codes to your virtual numbers.
- Make test calls and verify call quality or routing.
- Validate error handling for unreachable numbers.
5️⃣ Review Logs and Analytics
Check message delivery reports, call recordings, and other logs to debug issues and improve your workflows.
What Features Should You Look For When choosing a provider, look for:
- 🌍 Global number availability.
- 📞 SMS and voice support.
- 🔗 APIs for automation.
- 🎯 Unified dashboard.
- 🔊 Call recording & analytics.
- 💲 Affordable pay-as-you-go pricing.
Final Thoughts
Testing communication features is a critical part of app development — and virtual phone numbers make it much easier, faster, and more reliable.
We’ve been using KrispCall in our own projects to test SMS and call flows, and it’s helped us ship better products without the hassle of managing physical SIMs.
If you’re building apps that interact with phones, virtual numbers are a must-have.
What tools do you use for testing SMS and calls? Share your tips in the comments below!
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