DoinItFine, why is email any better than a text message? Either one would wake me up if I didn't silence my phone alerts overnight.
I reject your attempt to muddy the waters around what is synchronous and what is asynchronous. Making a phonecall to someone is a sign that you want them to be disturbed from what they are doing to have an immediate conversation with you (because that's how a phonecall works). Sending a voice message directly to their mailbox would be asynchronous.
SYNCHRONOUS (Immediate 2-way conversation requiring attention of both individuals at the same time - needs an immediate alert to the other party to allow it to happen)
Phonecall to mobile
Phonecall to landline
FaceTime
Face to face conversation
ASYNCHRONOUS (Disconnected messages which may be delivered immediately, soon, later, or possibly never, and don't require the recipient to be "involved" at the same time as the sender. Can be sent at any time because you're not demanding an immediate response. Recipient chooses when to read them and if and how they are alerted to their presence)
Text message
Email
Social media inbox message
Voice message sent directly to voicemail or via social media
Postcard
Again, if someone is trying to shift the onus of managing alerts for asynchronous messages from the recipient to the sender, they are being unreasonable, but a charitable sender might choose to respect their demands as best as possible, for the sake of peace and harmony. But let's not have it become the standard! (Luckily things seem to not be heading in that direction).