How can I use Countif to allow me to reference a cell that contains the area
codes of phone numbers to be counted? Below is my feble attempt:

=COUNTIF(Contacts!H3:H229,C4&"*")

where, C4 is the cell that contains the area codes to be searched. The "*"
must be employed, as the area code is only the beginning 3 digits of the 10
digit numbers in the given range.