The config looks ok, it may be a problem with the lines not all giving dialtone and you should try the test command to test each line for dialtone. The commands are entered from the Quintum prompt and are;
test o x (where x is the pstn port number to test)
test e (to end the test).
Again, for any further troubleshooting, I would need to access your system directly to see what is happening. If you need my support services on this, please contact me directly at firstname.lastname@example.org.