android sip to make calls to ucma application

Has anyone used the android sip stack to try and connect (establish a call) to a ucma app? Say I was running a ucma app that basically just listened for calls on port 5060 (ucma running in 'IVR Standalone Mode'). I know the Android SIP is likely not on the 'approved' list of compatible SIP 'clients', but was wondering if anyone has looked into it or tried.
Thanks.