la solution
<?php
$volume = shell_exec('curl -X GET http://192.168.1.10:3333/nad/c368/v1.0/Main/Volume');
$obj1 = json_decode($volume,false);
$obj2 = $obj1->value;
$volnew = $obj2 + 5;
$output = shell_exec("curl -X PUT http://192.168.1.10:3333/nad/c368/v1.0/Main/Volume/$volnew");
?>