How to change format of phone numbers in PowerShell?

Question

We need to append the area code and hyphen in front of the office phone number field in their domain user account for all our users that have office phones now that we are changing from 7 digit numbers to 10 digit numbers.
I found a script that finds and edits phone numbers, but the author chose a different way to format the numbers.
This is the part of the script I need to change:
# Format number as xxx xx xx xxx.
        $Phone = '{0}
{1} {2} {3}' -f$Phone.Substring(0,3),$Phone.Substring(3,2),$Phone.Substring(5,2),$Phone.Substring(7,3)
I'm trying to figure out how to edit that so that it formats it as xxx-xxx-xxxx
(3 digit area code, hyphen, 3 digit prefix, hyphen, four digit number) instead of xxx xx xx xxx.
Can someone show how to rewrite this section?

Answer 1

The modified script:
# This format number as xxx-xxx-xxxx.
$Phone = '{0}-{1}-{2}' -f $Phone.Substring(0,3),$Phone.Substring(3,3),$Phone.Substring(6,4)
Hope this helps.
Regards,
thennet
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