Phone number won't print in phone # format

I am using the new Report() function and have variables set in a JavaScript for a phone field and fax number field that are part of my pdf. One of the two won't print in the report in phone number format.
 
Both of these fields are formatted exactly the same as "special" phone number-formatted fields. I have the report set to include the data entered as follows:
 
rpt.writeText("Phone: " + Phone.value)
rpt.writeText("Fax: " + Fax.value)
 
When the report is generated the first field prints in the report as the 10 numbers in the field with no hyphens (and no spaces) after the area code and phone prefix; just the 10 numbers (i.e. 2345678910). The second field prints in phone number format, with correctly placed hyphens, i.e., 234-567-8910.
 
Any assistance in what may be causing the first not to include the hyphens while the second number does would be greatly appreciated.
 
David