Two issues after following your directions:
1. For the smartphone it worked. I was able to follow all the steps. However, at the end I get this message "softph300 Error while registering - Forbidden".
Now, this message started appearing during my initial attempts. Initially, since I was already using CsipSimple regularly on my phone, I decided to register the new user "softph300" without doing a new download. It would not register and I got the "...forbidden" message on that user and my other two existing users! Since I could not resolve the error, I decided to uninstall and re-install the app. This apparently has not solved the problem. I have a sneaky suspicion this all has to do with checking the "unknown sources" check box. For those who are more knowledgeable a solution to this would be very much welcomed.
2. Use Chrome. Avoid Explorer. How do I install com.csipsimple_1.02....apk after downloading onto my laptop?
Thanks