If you leave a voicemail, you're a boomer. You go by the old school cellphone etiquette. It's not efficient, but it's nonintrusive. We respect it.
If you leave a voice note, you're either a millennial or a boomer. You've been using cellphones forever. You say your piece, you move on, they'll get back to you when they can, no one has to deal with trying to talk at the same time.
If you trail your text with "..." you're Gen Z. Because you are a literal teenager, and being overdramatic is required. I used to put ellipses after my Facebook status lyrics in 2010.
If you answer the phone as soon as it rings: Boomer. That's no brainer. Listen, we millennials/Gen Z (zillennials?) people don't even want you to pick up when we call. We all have anxiety. When you pick up, you catch us off guard. We are only calling you because we absolutely have to because you are either a) customer service and our wifi is out b) a relative we are obliged to call in order to not upset some form of family system c) you haven't figured out another way to talk to us.
Which is also why millennial deem it rude to call without scheduling it first. At least send a text. We're gonna think it's an emergency.