This is a wall where in a local slum where people post advertisements for services that they are offering from lock experts, to laundry washing, moving, and computers. People walk past these walls and if s/he sees a service that they are looking for, they will call the phone number.
These kind of walls can be found in any community across China from middle-class to slum apartments. But in luxury apartments or more controlled high-rises, you don't see these kind of walls anymore.
In many places, you can see layers of papers pasted on throughout the years. Some places try to keep their walls clean, but they are unable to keep up with the pasters. Some pasters now stencil their number and services onto walls and stairs with paint.
What are the politics of wall phone numbers? Who posts these and how important are these to local community life? What will happen to these wall numbers when more people start using the internet for local services?