# this regex is based on the published list of international
# country dialling codes:
use constant CCODE_REGEX =>
  qr/2(?:1\d|2\d|3\d|4\d|5\d|6\d|9\d|[07])|
     3(?:5\d|7\d|8\d|[0-46-9])            |
     4(?:2\d|\d)                          |
     5(?:0\d|9\d|[1-8])                   |
     6(?:7\d|8\d|9\d|[0-6])               |
     8(?:0\d|5\d|7\d|8\d|[1246])          |
     9(?:6\d|7\d|9\d|[0-58])              |
     [137]                                /x;


sub strip_ccode ($)
{
    my $num = $_[0];
    my $ccr = CCODE_REGEX;
    $num =~ s/\+?$ccr//;
    return $num;
}