You can not evaluate a variable inside braces like this. You have to use a different style for the switch. Try this:
switch -regexp — $phone
$style_1 {echo “Style 1 found”}
{^[0-9][0-9]$} {echo “Style 2 found”}
{^[0-9][0-9][0-9]$} {echo “Style 3 found”}
{^[0-9][0-9][0-9][0-9]$} { echo “Style 4 found”}
{^[0-9][0-9][0-9][0-9][0-9]$} {echo “Style 5 found”}
default {echo “Style default found} 8)
