While writing below program few problems 1)so far it's doing what it's suppose to do ;
but I am sure it can be optimized..(rather, I am sure there are lot of mistakes) can someone please advise
2)I am not sure how to access inside of @data1, for example, how do I get total total number of %ipstn_s ?(beside doing ++ ), I thought I could just assign to scalar but ...

use strict;
use diagnostics;
use Text::CSV_XS;
use Data::Dumper;
my ($counter,$ncounter);
my (@data , @data1);

my @attrs_sto    = qw(  _status           
                        _gwname          
                        _acct_id
                        _call_duration  
                        _eoc_reason     
                        _call_direction 
                        _called_num     
                        _i_pstn_trunk  
                        _i_pstn_circuit 
                        _e_pstn_circuit 
                        _e_pstn_trunk );   
                                
my @attrs_att    = qw(  _status            
                        _gwname           
                        _acct_id
                        _eoc_reason      
                        _call_direction   
                        _called_num       
                        _i_pstn_trunk     
                        _i_pstn_circuit   
                        _e_pstn_circuit   
                        _e_pstn_trunk );  

my @attrs_sta    = qw(  _status           
                        _gwname          
                        _acct_id
                        _call_direction   
                        _called_num       
                        _i_pstn_trunk     
                        _i_pstn_circuit   
                        _e_pstn_circuit   
                        _e_pstn_trunk );   
                     
 
@ARGV = ('./sonuslog') unless @ARGV;
my $csv = Text::CSV_XS->new;
while (<>) {
        chomp;
        $csv->parse($_);
        my @fields = $csv->fields;
        my %rec;
        if (/^STOP/) {
              @rec{@attrs_sto} = @fields[0,1,2,13,14,16,20,33,34,36,67
+];
        } elsif (/^START/) {
              @rec{@attrs_sta} = @fields[0,1,2,11,15,28,29,31,53];
        } else {
              @rec{@attrs_att} = @fields[0,1,2,11,13,17,30,31,33,57];
        }
        push @data, \%rec;
}

my %ipstn;

foreach (@data) {
   my %ipstn_s;
   my %ipstn_a;
   $counter++;
       if ($_->{_status} eq 'STOP') {
          next ;
       } else {
           if ($_->{_status} eq 'START' && $_->{_i_pstn_trunk}) {
              my $i_pstn_si = extract($_->{_i_pstn_circuit}, $_->{_i_p
+stn_trunk}); 
              push @{$ipstn_s{$i_pstn_si}}, $_;  
              pushnow(\%ipstn_s);
           } else {
              if ($_->{_status} eq 'START') {
                  my $e_pstn_se = extract($_->{_e_pstn_circuit}, $_->{
+_e_pstn_trunk});
                  push @{$ipstn_s{$e_pstn_se}}, $_;
                  pushnow(\%ipstn_s);
              } else {
                 if ($_->{_status} eq 'ATTEMPT' && $_->{_i_pstn_trunk}
+) {
                    my $i_pstn_ai = extract($_->{_i_pstn_circuit}, $_-
+>{_i_pstn_trunk});
                    push @{$ipstn_a{$i_pstn_ai}}, $_;
                    pushnow(\%ipstn_a);
                 } else {
                    if ($_->{_status} eq 'ATTEMPT') {
                       my $e_pstn_ae = extract($_->{_e_pstn_circuit}, 
+$_->{_e_pstn_trunk});
                       push @{$ipstn_a{$e_pstn_ae}}, $_;
                       pushnow(\%ipstn_a);
                    } else {
                       $ncounter++; 
                    }
                 }
              }
           }
       }
}

print Dumper(@data1);

sub pushnow {
   push @data1, @_;
}

sub extract {
         return join('-', (split(/:/, $_[0]))[1,2], $_[1]);
}
[download]

example of output from above

$VAR14029 = {
              '11-57-USNxxxxxxxxxx' => [
                                          {
                                            '_acct_id' => '0xxxxxxxxxx
+xxxxxx',
                                            '_i_pstn_trunk' => '',
                                            '_called_num' => '5551213'
+,
                                            '_status' => 'START',
                                            '_gwname' => 'xxxxxxxxxxxx
+',
                                            '_i_pstn_circuit' => '',
                                            '_e_pstn_circuit' => '1:11
+:57:8:0:0x00000000:0x00000000',
                                            '_e_pstn_trunk' => 'USNxxx
+xxxxxxxxx',
                                            '_call_direction' => 'IP-T
+O-PSTN'
                                          }
                                        ]
            };
$VAR14030 = {
              '10-12-USNxxxxxxxx_D' => [
                                         {
                                           '_acct_id' => '0xxxxxxxxxxx
+xxxxxxxxx',
                                           '_i_pstn_trunk' => 'USNxxxx
+xxxx_D',
                                           '_called_num' => '5551212',
                                           '_status' => 'START',
                                           '_gwname' => 'xxxxxxxxxxx',
                                           '_i_pstn_circuit' => '1:10:
+12:22:8350:0x0001F8F0:0x00056940',
                                           '_e_pstn_circuit' => '',
                                           '_e_pstn_trunk' => '',
                                           '_call_direction' => 'PSTN-
+TO-IP'
                                         }
                                       ]
            };
[download]