Hi Jaime,
You might want to check fop2_server debug output and see if the Originate command works correctly, you can modify the fop2 init script /etc/rc.d/init.d/fop2 and change the OPTIONS line to read:
OPTIONS="-d -X 15 -l /tmp"
That will write an output.log file inside /tmp that you can later inspect. (you must restart fop2 in order for the change to take effect). Be careful as the log file will wrong really big, this is not something you might want to leave configured forever.
Another thing that you might want to do is update asterisk. Asterisk 1.2 is not *fully* supported, there are some features that will not work that you are missing already. Pehraps updating asterisk will help with your problem (or make it worst if you chose a broken chanspy release, there are many versions with chanspy semibroken in all branches, 1.4, 1.6 and 1.8).
Best regards,