Music on hold helps you increase retention, reduce churn, and even influence your caller’s attitude with hold music. Go on, get your elevator music jokes out. We’ll wait (and chuckle). We’ve all poked fun at Muzak, but the importance of hold music and its multifaceted nature may surprise you. Seventy percent of business calls go on hold. The main point behind hold music is to signal that the line is still open, but that’s not all it does. You can increase retention, reduce churn, and even influence your caller’s attitude with hold music.
Cordless Phones EnGenius DuraFon-SIP EnGenius DuraFon 1X EnGenius DuraFon PRO EnGenius DuraWalkie DuraFon-UHF-HC Dual-Mode Handset EnGenius FreeStyl 2 EnGenius FreeStyl 1 Voyager TM-2300

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.
Send that message, or get information needed, and press thumb button at bottom center screen/phone and all apps on “Home Screen” will return, If need to return to actual call in progress/or on hold, press the center button twice quickly.