The principle is simple - if you want your people to use the same lines, follow the same protocols, you have to write them down.
This manifests in a number of ways, the simplest being the call scripts used in the call center. Once you break through the IVR that front-ends it, that is.
"I'm sorry you're having problems with your car today," is what the roadside assistance operator always says right after I explain what sort of mess I've gotten myself into. Always. "Welcome to Mr. Meaty, would you like to try our super colossal suet melt?" is always what you hear when you roll up into a drive-through. Or some reasonable approximation thereof.
The bottom line is that we all understand how call center interactions are scripted. The point I'm trying (poorly) to make is that all of your customer touchpoints should be as rigorously documented and measured as the call center.
Here's an exercise. Off the top of your head, name all of the ways in which your company regularly communicates with your customers, the goal of each of those touchpoints, and how these touchpoints reinforce each other around a set of key messages.
Odds are you can't, and that's fine. You may say "that's marketing's job", and I'd be obliged to disagree. It's the job of the business - at the highest of levels - to ensure that it communicates consistently and effectively.
The other night we made meatloaf, mashed potatos and veg for dinner and my son asked "where's the gravy?" My wife responded "gravy doesn't just happen" - a much kinder response than the one I had planned, but definitely a better one.
Good communication "doesn't just happen". Unless you document how you communicate with your customers/market/staff, and measure how effective you are in each touchpoint, you can't guarantee consistency. If you're inconsistent, you're not effective, QED.
In Snowcrash, Neal Stephenson has this to say about franchises, and by association, communication:
The franchise and the virus work on the same principle: what thrives in one place will thrive in another. You just have to find a sufficiently virulent business plan, condense it into a three-ring binder -- its DNA -- xerox it, and embed it in the fertile lining of a well-traveled highway, preferably one with a left-turn lane. Then the growth will expand until it runs up against its property lines.