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?

Not really, it happens all the time.Some old fax machines need to hear a CNG tone from an answering fax and if people dial on there handset or speaker phone off the fax they are waiting for the same thing before they hit send when in fact they should hit "send" as soon as the line is answered.
Unles your actually using the DISA features,
(which I doubt) the KX-TA 62491 card was a waste of money.
The TVS 50 has auto fax recognition and instead of the "outgoing message" you can use the custom menus of the TVS 50.
This sounds like it may be for residential?

When you say the TVS 50 has auto fax detection, do you mean that you can program it to say "press X to send a fax now" and it goes to that extension? (Not very "auto) Or does the voicemail truly have automatic fax detection to send a call to a specified extension upon hearing the CNG tone? thanks, rich

Yes it has what you refer to as "truly automatic fax detection" that when set up properly it will direct a fax call to a fax extension upon a CNG tone.
MrG.

Thanks, got it to work. Youre right, that DISA/fax card is a waste of money. Wish I never bought it.

Rich, I e mailed you with my toll free #.
Your welcome to call.
MrG.