Can not get the Alcaltel FXO card to detect ringing coming from VG224 port. The Alcaltel FXO card works fine using an analog port from Nortel PBX or Verizon POTs line. On the VG224 voice port, I tried changing the ring frequency, ring dc-offset voltage, idle-voltage, ring cadence, reversed the tip/ring connections, all with no help. All other functions with VG224 and the Alcaltel FXO/FXS are working. Any thoughts on what else to check?