Not sure...I've not come across any sites that let me download calling sounds.
Its an interesting concept, though. A decent MP3 player with little speakers might work, but so would burning the sound to a CD and running through a mini player.
The migration over to digital sound off of stored chip media is a vast improvement over cassette tape playing technology. Sound is better, and less moving parts to go wrong in the filed, especially under harsh weather conditions.
If it isn't being done so already, I would vote this is a good "suggestion" to pose to the caller/sound companies out there. There might be some resistance at first simply because of their business setup is to sell sound bytes on fixed media. Security and delivery of downloadable sound files may be a whole new venture with startup costs involved. Can't hurt to ask the question, though, and at least get their minds turning.
