Texts and emails should be sent at the convenience of the sender and read at the convenience of the recipient.
THIS!
You only call a landline between 9am and 7pm, at a push - but taking into account family dynamics. The beauty of emails, text and other whatsapp is to send them without disturbing the recipient.
If the recipient doesn't have the right set up on their phone, it's not your fault!You have no control on the time the messages will arrive anyway. If people have a modern device (ie a mobile phone), then it's up to them to set it up properly. If they chose to have a landline only (which is fair enough), then you send them a letter if you are unable to call at "polite hour" - which is still a minefield, people sleep in the morning, nap, work, have lunch, give children a bath...
Many of us are in the train between 6 and 7am, it's the perfect time to catch up on text or emails. I wouldn't willingly bother anyone, but if they make it clear you can't text or email anytime other than 9 to 5, then I won't contact them.
I use my mobile as an alarm clock, never been awaken at night by it.
Still curious to know why a parent must be on stand by 24/7 when a child is at Uni. How do you cope when they go backpacking for a few months on the other side of the world? 