This is more of a 'business communication' question than 'security'.
When I was with my previous integration company, I had a very pronounced bias against employees using SMS for business communication: things like work orders, PO authorizations, and general business coordination belonged in email, not texts. Why? Because my IT platform had no engineering controls for SMS.
Our Exchange server was a core platform for the business. An employee could not say 'I never got that email' without IT being able to dig in and trace where the problem took place, and likely having a clear audit trail of what was actually sent.
I can't help but notice that SMS is becoming more mainstream. I met with an integrator this past week who primarily communicates with field techs through SMS. This seems really shortsighted to me, but maybe I just overamplify the weaknesses in my mind.
How about you? Regardless of which business you're in, how central is SMS to your communication?