[Action Script] Check if device has phone capabilites June,2012

Working on an app for Android and iOS that has a button that calls customer service using the following code:

PHP Code: url = new URLRequest("tel:+1-555-123-4567");
navigateToURL(url); 
This works fine; however, when tested on a device without phone capabilities (such as an old tablet), the button simply does nothing. From a user experience perspective, I'd like to add some kind of listener or something (such as a try-catch, or simple if-else) to show an error message when the device does not have phone calling capabilities.

Any ideas on how to achieve this sort of error-checking would be greatly appreciated.

Thanks in advance.
Check if device has phone capabilites

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