Linphone is great and important initiative in my opinion.
I came across some issues when registering new devices so I thought I point them out:
1. You cannot enter e-mail with "+" sign. It's a valid e-mail address sign used in aliases, however the form does not allow it.
2. You cannot change e-mail address using web manager. Is there another way?
3. If someone grabs your login and password he can delete your account without any confirmation via e-mail.