I have created a phonegap app which needs to communicate with a self signed SSL service.
I whitelisted my url in res/xml/cordova.xml like so:
The problem is you are using a self-signed cert. The Android WebView does not allow by default self-signed SSL certs. PhoneGap/Cordova overrides this in the CordovaWebViewClient class but does not deviate its behaviour by much; if the app is debug-signed, it will proceed and ignore the error, otherwise it will fail.
You could change the above-linked to code in your application and make the onReceivedSslError method always call handler.proceed() - but this isn't recommended. Don't use a self-signed certificate!