I am running CUCM 4.2 on cisco appliance, recently we are experiencing problem with the system because of the memory leak bugs on the version 4. My vendor suggests me to upgrade to 5/6 or i have to reboot my cucm every 30 to 60 days.
Do I need to buy that upgrade from Cisco?
You might need to purchase more than just the software. Personally version 5 is an island. Version 6 brings the 4.x and 5.x lines into one, but Version 7 offers more features and reliability. We had a bunch of version 6.x database instability issues. Weird things like all of a sudden configuration would go missing.
If you need to bump up, I would go with version 7, but you might have to purchase newer hardware to support it.
We hit the bug "high traffic please try later" appear on the phone screen, calls keep dropping. Cisco TAC said it is a memory leak bug in v4 and no way to solve without upgrade.
I really wonder if we can make use of any new features in 6 or 7.
"I really wonder if we can make use of any new features in 6 or 7. "
Well, even if you don't need or use any new features I think your users would probably think not having error messages and not dropping calls anymore to be a good feature ;)
As you said, v5 is an island, v6 has a bunch of bugs, v7 requires new hardware to support.
Very difficult to convince management to invest some much money (new hardware, new software,etc) just to solve one issue.
Today we hit another issue, some of the incoming calls reach our main switchboard and pick up by our receptionist, but there is no answer from the caller and eventually the callers hang up ang try again.
CCM 4.2 has now entered its end of software maintenance period (http://www.cisco.com/en/US/prod/collateral/voicesw/ps6788/vcallcon/ps556/prod_end-of-life_notice0900aecd806ec7a2.html), so if it is a newly identified defect it probably will not be fixed but you can increase your chances of getting a fix by picking up the most recent OS and CCM Service Releases.
Be sure to test all new releases in your environment and check the Release Notes for any small changes or caveats that might exist.