A lot depends on what kind of signs you want. A good place to start is a printing company that can print what you want and plasticize them in someway. Then all you have to do is to attach them to the building, either by themselves or put them in some sort of a frame. I would secure them decently, as kids etc, like to steal them and put them in their rooms. You can have a picture of a camera or the logo of your company on the sign if you want.

From past experience, most phone guys don't do too good of a job at this---perhaps a maint man of some sort can help you. That's what we did for some firestations that we put emergency phones outside for them. They eventually got signs and one of the guys made some nice frames for the signs and bolted them onto the side of the building.

Rockford VoIP