Federation can only be setup a few ways
- Intra domain (company.com federated to im.company.com)
- inter domain (company.com federated to abc.com)
- Intra domain partitioned (Company.com federated to company.com)
You need to define this to make any of the with CUPS 8.6.4 (you should run latest and greatest). Now, depending on which version OCS you have R1 or R2 is important as well.
Put the CUPS server in the domain you want it in. Some of the SIP paramenters can be pushed for Jabber 4 windows XML file IE: