Tap “Phone” on your iPhone’s “Home” screen and tap “Voicemail” to access your voice-mail settings. Tap “Greeting” and select “Default” if you wish to use the default greeting for your voice mails. Click “Custom” if you want to create a personalized greeting, and tap “Record” to say your greeting.
Calls will still technically be delivered to your phone, but your phone will not alert you to the call. This is a handset block and not a network block. You can put a network block on persistent telemarketers, but you need to contact your network provider for that. To view voicemails from blocked calls, go to Voicemail, then scroll all the way to the bottom and tap “Blocked Messages.”

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.
You’ve reached the voicemail of [your name], [your job title]. I’m currently either away from my desk or on the other line. Please leave your name, telephone number, and a short message after the beep, and I’ll be sure to get back to you as soon as I’m available.” Open the Google Voice app . At the top left, tap Menu. Settings. In the Voicemail section, tap Voicemail greeting. Tap Record a greeting. Tap Record . Record your greeting and when you’re done, tap Stop . Choose what you want to do with the recording: To listen to the recording, tap Play . Should you say your name in your voicemail?