I guess that you are using LDAP as the user provider but I don’'t know which field you are using to store the mobil number. A LDAP browser will help a lot to identify the right field name.
A) You can manually edit conf/openfire.xml and add this mapping - make a backup of the file before manually changing things in it. A restart of Openfire is required to read the new settings in it.
B) If you want to run the setup wizard again you may want to change “” in conf/openfire.xml and restart Openfire.