Hi Alexandr,

CCM 4.1 is built on a Windows Server 2000 platform and has been announced as End of Life. The feature set is getting a little old now and there have been many improvements in the more recent CCM Trains.

CCM 6.x is based on CCM 4.2(3) and incorporates that excellent feature set (on a Linux platform).Most people seem to find the Linux Appliance version of CCM much easier to work with. Upgrades can be done on "split partitions" so rolling back to the previous version is much quicker. The feature set in CCM 6.x is pretty vast and the 6.1(2) version seems to have most of the Bugs worked out (most ;-)

I think most people here would advocate going straight to CCM 6.1(2)

End-of-Sale and End-of-Life Announcement for the Cisco Unified CallManager 4.1

http://www.cisco.com/en/US/prod/collateral/voicesw/ps6788/vcallcon/ps556/prod_end-of-life_notice0900aecd806f41d9.html

Cisco Unified Communications Manager 6.x 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

http://www.cisco.com/en/US/docs/voice_ip_comm/cucm/rel_notes/6_0_1/601cmrn.html#wp44812

Hope this helps!

Rob