This API is used for adding Staff Reply
Please check example usage of Vision Helpdesk API

Operation : reply_ticket
Module : ticket

$postfields["vis_module"] = "ticket";
// This is the module under which you wish to perform operation

$postfields["vis_operation"] = "reply_ticket";
// This is the operation field

$postfields["vis_from"] = "Support";

$postfields["vis_ticket_post"] = "This is ticket post with html content";

$postfields["vis_ticket_id"] = 1;
// This is the ticket id to which you wish to post reply.

$postfields["vis_private”] = 1;
// 0 = do not display this post to client and 1 = show post to client

$postfields["vis_send_email”] = 1;
// 1= send email 0 = don’t send email to client

Below is API URL example for Reply Ticket

http://visiononlinedemo.com/support/api/index.php?
&vis_txtusername=admin
&vis_txtuserpass=21232f297a57a5a743894a0e4a801fc3
&vis_module=ticket
&vis_operation=reply_ticket
&vis_from=test@iamdemo.com
&vis_ticket_post=api_test1
&vis_ticket_id=242
&vis_send_email=1
&vis_private=1

OR use "access token" to Reply Ticket

http://visiononlinedemo.com/support/api/index.php?
&vis_txttoken=T0RSbU56TmpZemxoTlRabU1XWTJOV1ZtT0RWa1ltUm1NR1F6WldJell6VT0=
&vis_module=ticket
&vis_operation=reply_ticket
&vis_from=test@iamdemo.com
&vis_ticket_post=api_test1
&vis_ticket_id=242
&vis_send_email=1
&vis_private=1