The following settings control the sounds played to both the caller and the callee, in call begin and call end scenarios. The call begin scenarios also include tones for indicating PIN/password requests and suchlike. The latter have not been adjusted. It's not critical that these sounds are changed, and it may be better to leave the sounds to default.
By default the tones sound very much like the US system which can be disconcerting. When you're trying to work out what the unit is actually doing it's sometimes better that they do sound unusual. Distinctive sounds allow you to work out when you're hearing the SPA3102, and when you're hearing BT. It's up to you. If you want to play with the sounds and ringer cadences, then there is a primer in the links at the top left of the page, which explains how to build these strings of numbers.