Below are some of the the companies who have trusted Advanced Productions with their on hold messages and IVR greetings.
If you’re comfortable doing the recording in-house, but you aren’t sure how to put it all together, you could find a freelancer from a service like Upwork to handle this part for you. You’d select a freelancer to work with, provide them with your files and directions, and let them handle the rest.

On hold music & message on hold recording services available to businesses across Australia. Our on hold message recording uses the latest high quality recording equipment and editing techniques. We optimise our digital music on hold for phone transmission to ensure that callers receive a quality performance – our aim is to produce on hold messages and on hold music that keeps your waiting callers happy and holds their attention.
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.