Не секрет, что есть условно бесплатные (3000 минут) SIM-карты и если превысить
их лимит, оператор может узнать, что используется gsm-шлюз. Представленный
скрипт распределяет нагрузку и не звонит при превышении лимита по транку.
Список разрешенных кодов задается в файле в /usr/share/asterisk/agi-bin/cods.txt



 #!/usr/bin/perl

 # load module
 use Asterisk::AGI;
 use DBI;
 #use date::Format;



 # connect
 my $dbh = DBI->connect("DBI:Pg:dbname=asterisk;host=127.0.0.1", "asterisk_user", "passwd", {'RaiseError' => 1});


 my %trunks=("name1" => "SIP/994",
        "name2" => "SIP/993",
        "name3" => "SIP/992",
        "name4" => "SIP/991"); #89839

 my %trunks_id=("name1" => "994",
           "name2" => "993",
           "name3" => "992",
           "name4" => "991");

 my $Default_trunk="SIP/63762xx";
 my $Default_trunk_id="63762xx";

 my %calls=();
 my @calls_order=();

 my $LIMIT=2000*60;
 my $min=$LIMIT;
 my $min_trunk="name1";

 foreach $trunk (keys(%trunks)){
    my $sth = $dbh->prepare("SELECT sum(billsec) AS calltime FROM cdr WHERE 
      date_trunc('month',calldate) = date_trunc('month',now())  AND dstchannel LIKE '$trunks{$trunk}-%' ;");
    $sth->execute();

    while(my $ref = $sth->fetchrow_hashref()) {
    if($ref->{'calltime'} < $LIMIT){
        $calls{$trunk}=$ref->{'calltime'};
       
        if ($min > $ref->{'calltime'} ){
        $min=$ref->{'calltime'};
        $min_trunk=$trunk;
        }
       
    }
       if(not $ref){
          $calls{$trunk}=0;
       }
        }#end while
 }

 $dbh->disconnect();

 #@calls_order = sort { $calls{$b} cmp $calls{$a} } keys %calls;
 @calls_order = sort { $calls{$a} <=> $calls{$b} } keys %calls;


 #foreach $trunk (@calls_order){
 #    print "$trunk = $calls{$trunk}\n";
 #     $AGI->verbose("$trunk = $calls{$trunk}\n",3);
 #}
 #print "min $min_trunk\n";
 #$AGI->verbose("min $min_trunk\n",3);




 $|=1;
 my $AGI = new Asterisk::AGI;
 $AGI->setcallback(\&mycallback);
 my  %input = $AGI->ReadParse();
 sleep(1);
 my $num = $input{'extension'};
 my $caller_id = $input{'callerid'};
 if (!$num) {
        exit;
    }
   
 my $num1 = substr($num,1,6);
    my $syscmd1=`perl -ne "print if m/$num1/" /usr/share/asterisk/agi-bin/cods.txt`;
    chomp($syscmd1);   
    if($syscmd1==0){
       $AGI->exec('Playback', "/var/lib/asterisk/sounds/record/blocked_call");
       exit;     
    }
   
 my $use_default=1;
   
 #$AGI->stream_file("/var/lib/asterisk/sounds/record/limit_call","*");
 $AGI->exec('Playback', "/var/lib/asterisk/sounds/record/limit_call");

 $AGI->verbose("Executing Dial $num $num1 $caller_id  $syscmd1 \n",3);
 foreach $trunk (@calls_order){
    $AGI->set_callerid($trunks_id{$trunk});
    my $syscmd=`asterisk -r -x "core show channels" | grep "$trunks{$trunk}"| wc -l`;
    chomp($syscmd);
   
    if($syscmd==0){
    #$AGI->verbose("????? Status $trunks{$trunk} '$ret' '$status'\n",3);
#        my $ret=$AGI->exec('Dial', "$trunks{$trunk}/$num");

        my $ret=$AGI->exec('Dial', "$trunks{$trunk}/$num|120|L(191664)");
    my $status=$AGI->channel_status();
   
        if( ($status==0 || $status==1) && $ret!=1 ){
        $AGI->verbose("????? OK! $caller_id $num ret=$ret status=$status syscmd=$syscmd\n",3);
        $use_default=0;
        last;
    }else{
        $AGI->verbose("????????? error $caller_id $num $trunks{$trunk}/$num '$ret' status=$status  syscmd=$syscmd \n",3);
    }
    }
 }

 if($use_default==1){
    $AGI->set_callerid($Default_trunk_id);
    my $ret=$AGI->exec('Dial', "$Default_trunk/$num");
    $AGI->verbose("????????? error_Default_trunk $caller_id $num $Default_trunk/$num ret=$ret \n",3);
 }

 sleep(1);
 exit;

 sub mycallback {
  my ($returncode) = @_;
    &log("CALLBACK");
    &cleanup;
    #print STDERR "User Disconnected ($returncode)\n";
    $AGI->verbose("!!!!!!!!!! ($returncode)\n");
  exit($returncode);
 }