[Asterisk-Users] Anyway to customize ring tones on aastra phones?

[William Harrison]

If you mean can you download rigtones to the Aastra IP phones, then no,
that is not possible.  

However, there are 5 different ring tones, 6 if you count Silent, which
was added in 1.4.0, that can be selected on the phone, via its cfg file,
Phone UI, or Web UI.

This is explained in the 1.4.0 IP Phone Admin Guide, under Operational
Features, in the section labeled "Ring Tones and Tone Sets".