Question: Do all phones allow programmable ringtones?
Answer: Not always, and there is a lot of confusion about that. Older phones, and the majority of phones manufactured for the North-American market before the year 2002 don't offer that feature.
While most phones offer customizable ringtones nowadays, some models block users from adding ringtones themselves in a free, do-it-yourself manner, in some cases because the networks are asking them to do so, in order to force users to buy ringtones from them. For the most recently updated list of ringtone-compatible phones, see the link below: