I think perhaps you want to do the opposite of this (remove the periods, not
add them) - if so that could be done by
=SUBSTITUTE(A1,".","")

"Jim Thomlinson" wrote:

My personal favorite thing to to is to remove all non-numeric characters and
then use a custom number format to make the number look like a telephone
number again something like (###) ###-####. That being said numeric format
will not work with multiple periods. So if your heart is set on periods then
you need to use the formula
=LEFT(A1, 3) & "." & MID(A1,4,3) & "." & RIGHT(A1, 4)

--
HTH...

Jim Thomlinson


"childofthe1980s" wrote:

Hello:

If you have a phone number in a cell such as 800.555.1212, what formula do
you write for that cell to make it 8005551212?

Thanks!

childofthe1980s