Reply To: phone on mails

so, if in the form I’m using:

Phone
Your phone number?
[custom text thephone *]

in mail I should use: [thephone] , [custom text thephone]?

I’m trying with both and inside mail I can see:

Phone [custom text thephone]
or
Phone [custom thephone]

depending, but in any case the phone number, What m I doing wrong?