Hi! I understand you're having trouble making calls from your Vonage Business Communication app on your mobile device. Let’s get this sorted out together.

To start, could you please tell me:
- What kind of mobile device and operating system version you are using for the Vonage app? (e.g., iPhone iOS 15, Android 12)
- Are you able to open the app without errors, or does it crash/ freeze?
- Have you noticed any error messages when you try to make a call?
- Are calls inbound working, or is it only outbound calls that don’t work?

Meanwhile, here are some initial steps you can try on your mobile device:
1. Restart your phone to clear temporary glitches.
2. Ensure your Vonage Business Mobile app is updated to the latest version available on the App Store or Google Play.
3. Check that your phone has a stable internet connection (Wi-Fi or cellular data). Try switching networks if possible.
4. Log out of the app and then log back in to refresh your account session.

Let me know what you find from these details and actions, and we can proceed further!