I don’t like the alarm metaphor used on mobile phones. That sound was useful when people had only one hard-wired telephone in their house and needed to be alerted to a call coming in. They might have had to hurry to the room the phone was in, in order not to miss the call. Then came the answering machine, which meant one could miss a call and deal with the caller at a later time, but the alarm sound remained.
Now many of us carry a mobile phone on our person most of the time. The phone no longer needs to sound a terrible alarm every single time a call comes in. A gentle announcement would suffice, I think. In fact, it would make quite a difference for a caller to be gently announced, rather than hearing a full alarm sounded. One can always check who called, unlike with the early telephones, and there is the built-in answering machine, too.
With that in mind I created a few ringtones you may download. Try them out, see whether the idea works for you.
and if you need something a little stronger, try one of these, from Nouveaumatic:
Personally, I use the solo trumpet beginning of “Nature Boy” by Jon Hassell. You can find piece that on iTunes.