Following the information you were given, enter the following information in your SIP Client:
User ID (extension)
Domain (FQDN from your OXE virtual lab)
Password
Authorization name (same as your extension)
Transport UDP and port 6260 (the routing is done via a SBC)
At this point, you should be able to login and dial a test number like *0# (it will list all the tones of the OXE, starting with a RING).
*IMPORTANT NOTE*: Make sure you are using G711-MuLaw CODEC.
Call *0# - This will play all tones feedback (starting with the RING one)
If you did setup 2 extensions, you can either call the direct 4 digits number, or dial 91xxxyyyzzzz (9 is the prefix, 1 is mandatory for the dialing plan, xxx and yyy are random numbers, zzzz is the extension you want to receive the call to).
This last example will simulate a phone call going out, then back in to the system, through a SIP Carrier emulator.