There doesn’t seem to be a way to adjust the answer time or the ring tone. This means that there’s no way to do any sort of distinctive ringing or play an audio file for a ring tone based on incoming CID. Others have similar comments at Ringtone use
No ring tone capabilities, CID capabilities, or tone capabilities
Thank you for your feedback, we noted this issue already and we are still working on this issues. We will be replying on the initial post regarding this issues.
Initial Post: Ringtone use