I have KX-TA624/TVS50 with ogm/fax detection card. Most faxes come thru a-ok, but sometimes the ring will be longer and of a different tone and the fax will not connect, eventually the call rings to the receptionist's desk. When querying the senders we have found that they either have an old fax machine or are using their speakerphone option. Any way to fix this annoying problem on our end?