Users are not allowed to edit their own one key rules since it requires they link to system objects (call handlers) and such which is reserved for Admins only.
In Unity 4.2 you have the option of letting users set the transfer string on one user input key the admin sets up for users so they can set it to their own home phone, cell phone or the like - but admins have control over whhich key is mapped for this purpose (if any). Users can control only the number it transfers to.