Try this:
Using cell A1
Set the numbe format to Special and select Phone Number

Then:
DataData Validation
Allow: Custom
Formula: =ISERROR(FIND("-",A1))

If length is an issue:
Use this validation formula instead:
=AND(LEN(A1)=10,ISERROR(FIND("-",A1)))

Does that give you something to work with?

***********
Regards,
Ron


"kclover" wrote:

I am trying to format a range of cells not to except dashes (-) ie. when
entering phone numbers 123-123-1234