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.
5.0 out of 5 stars Solved our royalty-free hold music problem It works perfectly as advertised and solved our royalty-free hold music problem. When it arrived, we installed it with our office telephone system and have never needed to worry about it again. It has such a wide selection that callers get different music every time they call - it does not noticeably repeat. We even got a few compliments from clients in the first month (who had apparently got tired of our old 45-second repeating loop). Terrible product, will not work at all I have purchased 2 of them hoping it was a glitch but neither work, in addition I called support, no help at all, said they would call back-never did.

The main objective of a caller navigating an IVR system is to get to the desired destination as quickly as possible. If the script contains overly wordy phrases and long descriptions, the callers will get frustrated with every passing word.
Whether you have a group of 2 players or 2,000, our elegant user interface makes it simple and easy to manage productions & scheduling on groups of devices that you define.