If you're running a newer version of CUCM (6+) then SIP-SIP is preferred. There are many things that are handled differently when CUBE has to translate H323 into SIP.
One of the factors is whether or not you will need an MTP. For the SIP-H323 connection you'll need an MTP for every connection to do supplementary services. For SIP-SIP you will not. There is a feature available for SIP-SIP called DO-EO or 'forced early offer' that allows CUBE to send an SDP before receiving one.
You'll find greater 'transparency' and les issues with a SIP-SIP CUBE than you will for H323-SIP. If you have a CUCM 5x or older, the SIP stack isn't as good however, and you may want to stick to using H323-SIP with an MTP.
Nicholas is correct in his statements. CM 4.1 does a poor job in talking h323 to SIP. In most cases you will need an MTP to establish the calls. If you are low on MTP resources or none exist, the call may not complete or supplementary services will not work.
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...