Support of more
than one Extension Number per Work Center. 
Use
More than one extension number can now be maintained for each work center. The extension numbers may be of different types. There are two types for 4.6C: One is for the basic functions of SAPphone, such as initiating and accepting calls (BasicPhoneFunctions DN) and the other is for call center functions (QueueDN).
For more information, see the documentation on SAPphone and the Customer Interaction Center.