Hey there,
i tested IOS 9 Beta 1 on my iPhone 5s. IMESSAGE and FACETIME could be activated without any problems.
No i did a downgrade to IOS 8.3 and have now the problem, that i stuck in IMESSAGE and FACETIME ACTIVATION.
If i install IOS 9 again, both could be activated.
I also did a clean install (DFU-Mode) and set as new device.
Please help ...
Greetz Tommy