What format must telephone numbers in address books or databases have?

Must the XPhone Client or virtual directory address books or databases contain phone numbers in canonical format, e.g. +49(89)123456?

XPhone or the Virtual Directory accepts all common formats. This ensures reliable caller identification and correct dialing. 

However, it is important that in no case the outside line access / outside line reason, e.g. a 0 (zero) is put in front of the call number. 

Examples of permitted formats: 

+49(89)123456-78  
0049-89-123456-78  
+49(0)89 123456-78  
089/12345678  
089.123456.78 

etc.