At this point, we can’t be exactly sure why your iPhone won’t play voicemails. The voicemail you play in the Phone app on your iPhone is called Visual Voicemail, which downloads your voicemails from your carrier in the form of little audio files, similar to the music files you listen to inside the Music app.
Whatever situation you’re in, there are times we find it necessary to avoid making certain important calls. Instead, you may prefer leaving a voicemail. However, if you simply call the person’s phone number, they might pick up and not give you the chance to leave a voicemail.

You might also consider giving them the option to skip your voicemail message completely by pressing another key (again, check with IT). You also want to make callers aware what you will return their call, instead of telling them that you will try to return their call--and let them know when you are likely to do it, if possible. If necessary, provide additional or emergency information in your voicemail greetings. My dentist, for example, lists his cell phone number for emergencies.
The earliest voicemail applications have been purchased by other messengers, and now there are new, but little known ones. We have selected 11 free and convenient voice mail applications for you, designed for iOS and Android. YouMail. Visual Voicemail & Missed Call Alerts – InstaVoice. AT&T Voicemail Viewer.