The average phone hold time is 15 and half minutes. That's long enough for your customer to get frustrated. It's long enough for him to forget why he's calling you. It's long enough for him to take his business somewhere where he feels they'll prioritize him.
Your customer does not want to compete with technology issues. Your employee should never have to face the decision: do I give the customer quality service, or do focus on the glaring IT needs?
You can do BOTH when you hire a team specifically cut out for managed IT work.