I have to add in defense of messages possibly being ignored or unreturned, and at the same time condemn Verizon Wireless. Maybe it's just out state that has problems with not getting phone calls or voicemails.
1) I can be sitting right here with the phone, it doesn't ring but will alert me to a "missed message".
2) I can be sitting right here with the phone, DH and my Mom will test and call me from the same room. No ringing, no message alert. I'm sitting right there. I call them to test, DH's rang, Mom's did not.
3) This one is REALLY a problem: voicemails not showing up for as many 10 days up to 3 weeks after they're left. In some cases, I'm expecting an important (doctor died) message and when it doesn't come as scheduled, I call various times throughout the day, every day. Nothing. Three weeks later, I get a New Message alert! I listen to the envelope and it tells me that it came in three weeks ago, but that's not true. And it's unacceptable because people swear they left a message, but I'm not getting it, they don't believe me and think I'm ignoring it until it happens to them.
4) Our flip-phones (go ahead and laugh, I do) don't have text capabilities, so I don't know about those issues if there are any.
Our phones are on, charged and ringers on with signals. DH is a tech guy, so we are thorough (anal) in our tests and experiments. It's hit and miss.
We know the difference between messages that are left at the time of the call and when calls are left strictly as messages without making an actual phone call, like coming in through the backdoor as not to disturb someone with the alarm or worry of a ringing phone in the wee hours.
A call comes through fine, two minutes later, it goes directly to vm, but we might not get it for days or weeks even though we call in to retrieve messages, they sometimes won't be there even though we're sitting next to each other and hear the message at the time of leaving.