#! /usr/bin/perl
use strict;
use warnings;

use 5.010;

my $known   = "Name Vornamesip:0813893511\@b2b.domain";
my $unknown = "0813893511sip:0813893511\@b2b.domain";

# reformat one caller string
sub reformat_caller {
        my $caller = shift;

        my ( $name, $number ) = split m{sip:|@}, $caller;

        # use $name as long as it does not contain only digits
        my $result = $name . " "        if $name !~ m/^\d+$/;
        # alternative, $name should not be the same as $number
        #my $result = $name . " "       if $name ne $number;

        # always use $number 
        $result .= $number;

        return $result;
}


for my $caller ( $known, $unknown ) {

    # pretty print caller string
    say reformat_caller($caller);

}