For those still using analogue or digital phone systems, voice on ISDN circuits has a bandwidth of around 4000Hz. The audio from an analogue phone is sampled at 8000Hz, and because of the nyquist theorem, must be low-pass filtered to 4000Hz. So any frequencies in the audio beyond 4000Hz are lost. Interestingly, the human ear and mind are good at recognising human speech, so this is considered "toll-quality" voice, i.e. good enough to pay for. This is the reason why certain vocalised letters are difficult or impossible to tell apart on the phone. For example, the differences between B, P, T, C, etc. are almost entirely above 4000Hz.
Create your script, choose your audio artist, your music and before you know it, your words are taken off the page and brought to life.

These digital systems come with different loading options including remote load, CD load, USB load and Internet Download. Typically we work with your telephone system contact to determine which digital player fits your needs and telephone configuration the best.
“Evolved Sound’s phone on hold solutions will exclude your business from paying any licence fees to any regulatory or governing body, resulting in significant yearly savings, particularly when multiple lines exist.” Finished telephone on hold messages are mixed with complimentary music and finalised for best playback quality to callers.