Hi,
I assume you are talking about Native Call Queuing which was introduced with CUCM 9 ? If so then its not strictly a call centre however you could use barge feature to get another party into the call;
http://www.cisco.com/c/en/us/td/docs/voice_ip_comm/cucm/admin/9_0_1/ccmfeat/CUCM_BK_CEF0C471_00_cucm-features-services-guide-90/CUCM_BK_CEF0C471_00_cucm-features-and-services-guide_chapter_01.html
You can also use the Queue Status phone button to display statistics for the queue, these do not refresh in real time so you would need to press the button for it to update;
http://www.cisco.com/c/en/us/td/docs/voice_ip_comm/cucm/rel_notes/9_0_1/delta/CUCM_BK_N38FD301_00_cucm-new-and-changed-90/CUCM_BK_N38FD301_00_cucm-new-and-changed-90_chapter_011.html#P790_RF_P92537AF_00
Regards,
Richard