You may find some checks complain of missing utils.pm. If you do, check if the script is making any references to the nagios plugins directory. You may need to alter the path to /usr/local/nagios/libexec/ .
Be sure to inspect any firewalls between your Nagios server and the sipXcom/openUC servers prior to running your checks. Some services such as ssh are restrictive by default in the sipXcom/openUC firewall.
It is possible to utilize sipsak to test against the SIP stack, however by default sipXcom / openUC will block the sipsak user agent and blacklist the source address it came from in iptables. Be mindful of this and try not to cause unnecessary stress on the server with your service checks.