Randy,
There are several examples in the SIPr distribution itself.
I am assuming you have written (or generated ) a controller that has on_invite() method implemented.
If everything is setup correctly, I would ask you to take a wireshark capture of the message and look at the INVITE that is received on the server where SIPr is running.
You should receive the message, if you have the SIP message then it should have the right IP and Port (the ones on which SIPr is listening)
If that is fine too then enable SIP debug logging (have a look at log4r.xml) and then see the message in the SIPr logs.
If you are not able to see controller handle the message then the logs will have information on why it was rejected or not processed.
Usually the problems will be at the sending end or setup where SIPr listen points are different.
Hope this helps.
Thanks
Nasir