Correct in CUCM 6.1 everything was DLU driven and no distinction between was done between different levels. Simply use the built in calculator to come up with number of DLUs you need. You may not be able to purchase more DLUs as those are I belive EOS so the reseller (use Cisco partner) can convert those into UCL or CUWL licenses for you.
Also, consider upgrading as 6.1 has been EOS for some time, and will soon be no longer supported (September 30, 2013):
SIP traces provide key information in troubleshooting SIP Trunks, SIP
endpoints and other SIP related issues. Even though these traces are in
clear text, these texts can be gibberish unless you understand fully
what they mean. This document attempts to br...
Please find the attached HTML document, download and open it on your PC.
This provides an easy to use form where you simply answer a few
questions and it will render the proper jabber-config.xml file for you
to copy/paste. There is built in logic to verif...
CUCM Database Replication is an area in which Cisco customers and
partners have asked for more in-depth training in being able to properly
assess a replication problem and potentially resolve an issue without
involving TAC. This document discusses the bas...