Here's a fragile "stab in the dark" approach to supposition one:

my $result;
if( $aa =~ m/From:\s([^@]+)@/ ) {
    $result = $1;
    $result =~ s/\s</</g;
}
[download]

And here's a fragile "stab in the dark" approach to supposition two:

my $result;
if( $bb =~ m/UDP\s*([\d.]+);/ ) {
    $result = $1;
}
[download]

These examples will handle the narrow examples you've provided, but are nowhere near fully complient SIP handlers. If you want a robust solution you'll need to give more information on what you're actually trying to do.