Hi Saeed,
Good question! In fact CUCM 6.x is more Feature rich than the 5.x versions. CUCM 6.x was built based on CCM 4.2 and CUCM 5.x was built based on CCM 4.1 and thus the features carry across as such. Most people who are building new CUCM deployments these days are skipping directly to CUCM 7.x which has proven to be an excellent build. My vote would be to definitely skip 5.x
here is the related CCM 5.x and CCM 6.x info :)
Cisco CallManager 5.x Features
Call Forwarding Enhancements
Call Park
Call Pickup Group
CTI and CTI Super Provider
Dynamic Host Control Protocol (DHCP)
International Dial Plans
LDAP Directory Enhancements
Licensing
Personal Directory Enhancements
Phone NTP References for SIP Phones
Presence
Roles and User Groups
RSVP
Service Enhancements
SIP Line Side (Endpoints) Support
SIP Route Pattern
SIP Third-Party Phones
SIP Trunk Enhancements
TFTP Enhancements
URL Dialing
Video Telephony Enhancements
Voice Quality Metrics
http://www.cisco.com/en/US/docs/voice_ip_comm/cucm/rel_notes/5_0_1/501cmrn.html
Cisco Unified Communications Manager 6.0 feature enhancements:
•AAC/iLBC Voice Codec Support
•Advanced Ad Hoc Conference
•Audible Message Waiting Indicator
•Barge Enhancements
•Call Diagnostics and Voice Quality Metrics
•Call Forward Enhancements
•Call Forward All Calling Search Space Backward Compatibility
•Call Forward Overriding
•Call Pickup Notification
•Cisco Messaging Interface Enhancements
•Cisco Unified Communications Manager T1 CAS Hookflash Transfer Support
•Connected Number Display
•Credential Policy and User Authentication
•CTI Enhancements
•Device Mobility
•Directed Call Park
•Do Not Disturb
•Hold Reversion
•Intercom
•Licensing Enhancements
•Log Out of Hunt Groups
•Overlap Sending and Receiving for H.323 Gateways
•MGCP T.38 Enhancements
•Privacy on Hold
•Programmable Line Keys
•SCCP Optimization
•SDL Traces
•SIP Endpoints Support
•SIP Third-Party Phones Enhancements
•SIP Trunk Enhancements
Release Notes for Cisco Unified Communication Manager Release 6.1(3a)
http://www.cisco.com/en/US/docs/voice_ip_comm/cucm/rel_notes/6_1_3/cucm-rel_note-613a.html
Here is the latest and greatest:)
Release Notes for Cisco Unified Communications Manager Release 7.0(1)
http://www.cisco.com/en/US/docs/voice_ip_comm/cucm/rel_notes/7_0_1/cucm-rel_notes-701.html#wp580948
Hope this helps!
Rob
