Unusual sound files on TP

[saqer]

This may be very trivial but it still sparked a question within me. I was looking through some of the stock sound files and HTC seems to have included the sound of a dial tone and the ringer your hear when dialing out. What possible purpose could this serve? Both would make pretty lame ringtones imo. Could this be some indication of a call screening feature or something along those lines? I know Windows Mobile are crippled when it comes call recording and call screening/answering machine but it would be interesting if that's a possibility with the TP down the line.