http://valinet6l6tq6d5yohaa6gdsf2ho4qcqcxyj2nahp5kd4z7nsa6ycdqd.onion/2015/07/01/How-I-exported-my-text-messages-from-Windows-Phone-to-Android.html
And when the app is not official, weird formats may be used, which may render the portability of the generated file useless. Anyway, Google is saved by the community and its openness regarding Android APIs. On Windows Phone, a developer doesn’t have access to the Messaging APIs, so he can’t replace the default Messaging app or handle text messages in any way.