Phone call ring then voicemail sometimes and then goes right to voicemail no ring what does that mean phone off or ignoring call. I have metro pcs and my phone rings once then goes to voicemail when someone calls what could be the problem?
On the iPhone, go into voicemail and tap "Greeting". Record a few seconds of something and tap stop. Before you tap save, use iFuntastic or SFTP to navigate to /var/root/Library/Voicemail on your iPhone. You'll see a file called "Greeting. amr". This is the audio you just recorded. Delete that file and replace it with your custom message which should then be renamed to "Greeting.amr". Tap "Play" on the iPhone to verify your message works. If it plays, tap "Save" and your custom message will be uploaded to AT&T's servers.

Many people don’t even know about this PIN option, so they never get around to changing it to something a bit more secure. That’s how the whole News Of The World hacking scandal came about, so you should always remember to create a new PIN for your voicemail that will be harder to guess. And if you’re even remotely famous it’s probably worth changing it every few months as well.
I can't get to the phone before it goes to voicemail. I understand that the number of rings the caller hears is controlled by my carrier, Verizon. My husband has a Samsung Galaxy S7 purchased from Verizon and when he calls, he hears 8 rings then it goes to VM. Note that I called Verizon and they set it to 8 rings, the maximum available.