I now seem to get consistent results depending on the model of the sending fax machine. It fails consistently with a Dell MFP Laser 3115cn (a multi function color laser printer/scanner/fax), but works consistently from a Panasonic KX-MB1520 (a multi function laser printer/scanner/fax). I'd like to do some tests from fax machines of other models, so if you have a FAX machine handy, please contact me off the list and I'll give you my test fax number.

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Steve