U200 yeasrat

Hello.We have a problem with yeastar u200 on which FXO of a board are set and sip trunk on freeswitch is set up. The problem is that the hangup doesn't work when clients ring on numbers. Our region is Azerbaijan Baku. We tested our frequency and there were such settings the frequency 450, volume 15,7. Duration is 250 msec. Interval of following 500-800. What settings to us to make on u200 that the release worked?