Business communication is increasingly using text messaging over email, especially since many emails are in fact apologies for not responding sooner due to the number of emails received!
There are studies linking frequent email checking with higher levels of anxiety and heart activity suggesting higher levels of cortisol, itself associated with stress. Most executives are no longer desk-bound and handling email via a smartphone is cumbersome. Even Lawyers now text clients, and may not charge for that time whereas every second of a phone call is billable. Facebook also claims their messenger service has doubled to 1 billion messages in the past year.