Non urgent communication definitely is e-mail but it has to be non-urgent stuff
Personal visits for coaching, teaching, operations
I use text messaging for urgent stuff/get with me stuff
I try to stay off the phones with them because it takes them away from running the business as most times they are with a guest or employee. They can call me after they get a text message from me when they are not engaged with the guest or team
Personal visits to teach, train, and support which creates a trained and motivated manager. Personal visits to maintain the relationship and give the message. All other forms of communication leverage the relationship and reinforce the message. All other forms of communication count on the properly trained and motivated manager on the receiving end. Many Multi-unit managers over use their blackberries and get quite lazy as leaders and managers. Dont allow technology to get in the way of building trusting relationships with your staff.
Text messaging has become very popular. Some of our MUM's have a daily fax sheet that goes out to all restaurants with "rack and stack" numbers in the morning. As Andy stated, phone calls are a last resort because it takes the manager away from running the restaurant.
Restaurant visits are the logical time to reach as many of the team members as possible.
I agree with much of the sentiment relayed. Text messing and email are great to keep moral, but their is nothing compares to rolling up the sleeves and taking time through a personal visit.
One method that I did not see posted was a weekly call in from each manager. You pick the categories that you want them to focus on. Daily and weekly labor (shift or store specific), staffing levels for their work groups, productivity, personal development any personal assignments that you specify to that individual. They call you and you tag them back. It always keeps the lines of communication open. They feel better about their environment and you have something to coach, teach and hold accoutable.