Generally, cell phones are mapped to a number and device ID regardless of the implementation. That is how the call finds you. I am not aware of any cell providers that allow for multiple cell phones for a single line, predominantly because the routing software does not allow for multiple device addresses. Although, with the number of customers moving to cell only and getting rid of their land lines, this may be in some cell companies plans. Estimates say that 40% of all cell users have no land lines at their home.
This was first published in August 2003