Integrating your iOS app with Avaya Communicator

Question

In iOS, I am trying to make a call using Avaya Communicator from app by opening a URL with the avaya-onex-call custom scheme.

 NSString *dialString = @"+14085550101";
    NSURL *url = [NSURL URLWithString:[NSString stringWithFormat: 
    @"avaya-onex-call:%@", dialString]];
    // Try to launch using the Avaya Communicator app
    if ([[UIApplication sharedApplication] canOpenURL:url]) {
    [[UIApplication sharedApplication] openURL:url]; 
    } 

I was able to navigate to Avaya communicator from my app and a dial pad is displayed in Avaya communicator. But within in a fraction of seconds Avaya app crashes/Closes without any call.

I am using the iOS app in India and I have configured VoIP services. With the same configuration details my colleague was able to call the number through Avaya in US in Android. Please suggest.