Directional signs and doorplates show the location of companies.
All office buildings need directions for their customers to navigate around in the building, to find the wing, floor, corridor, door, and person they are looking for. In order to avoid making people run around your building not knowing where to go, it would make sense to install directions and signs in the building. You can use the time gained by these clear directions, for communicating with your customers.
If you have a large territory, it should be made as easy as possible for customers to navigate.
A customer will be happy if he or she discovers, upon entry, that the a building not only has a nice atmosphere, but also has clear directions for finding their way around. A door must have a doorplate in order to be identified properly.
For displaying advertising signs and notices, consider installing an information board specifically meant for that purpose.