If you don't have access to curl() PHP function, then you can use fsockopen or see if you can use curl via exec if curl is installed on the server.
$arr = array(); # capture output if any
$result = FALSE; # return code from curl
exec($path_to_curl, $arr, $result);
Might have to send some switches and obviously your args to curl as well.
Always be careful when calling exec(): validate the data and escape strings. To find path to curl write a script that says something like:
$result = FALSE;
$arr = array();
exec("which curl", $arr, $result);
print_r($arr);
All my 'bot' projects have been in perl, not php. Just simpler IMHO.