In the UK (I worked for BT in areas close to this) you can not give out a personnal address when given a telephone number. However if you are looking for a business address you can phone a directory service such as 192 (now 118 500) and provided you have the company telephone number & Name they may issue you with an address.

Actual reverse look-ups of personnal telephone numbers is not allowed by any UK company. It does not matter if the person is listed, XD/NC or XD/CO (exdirectory/No calls exdirectory/Calls offered - XD/NC is common format for unlisted numbers....XD/CO means that the number is not listed in phone books but by calling the operator they can call the number for you....without disclosing it - and see if they would like to accept the call)

v_Ln