A phone line has opening hours and a queue. A message does not. The people who will not wait on hold are messaging you right now, and nobody is reading it.
In the channel they chose, in the language they used.
Same knowledge as the phone line. One brain, not a second setup.
When it needs a person, the conversation arrives summarised.
Yes, through an official business provider, not a browser workaround that breaks every update.
Yes. It is one employee across channels rather than one tool per channel.