Yes, this is possible.
What type of devices are you trying to register to the CUBE? SIP endpoints I'm guessing?
To simply enable the registrar, it is this command:
voice service voip
sip
registrar server
If you want to enable calling between endpoints registered to the SBC, you would need SIP CME.
This is what the minumum required configuration looks like:
voice service voip
sip
registrar server
voice register global
mode cme
source-address 1.1.1.1 port 5060
max-dn X
max-pool X
voice register dn 1
number 1000
voice register pool 1
id mac XXXX.XXXX.XXXX
type ! If it's 3rd party, omit this
number 1 dn 1
username X password X ! Required if IP phone's address is on different subnet than SIP CME source address
You can also look at the documentation here:
http://www.cisco.com/en/US/docs/voice_ip_comm/cucme/admin/configuration/guide/cmesystm.html#wp1025405
http://www.cisco.com/en/US/docs/voice_ip_comm/cucme/admin/configuration/guide/cmebasic.html#wp1073239
hth,
nick
