Sending SMS on WebForm after_save

I want to send SMS on after_save event of WebForm and I have to send it without the user logged in. The WebForm is publically accessible and user does not have to be logged-in to submit the form.

My problem is erpnext is giving the following error

  File "apps/frappe/frappe/", line 66, in application
    response = frappe.handler.handle()
  File "apps/frappe/frappe/", line 38, in handle
    data = execute_cmd(cmd)
  File "apps/frappe/frappe/", line 73, in execute_cmd
  File "apps/frappe/frappe/", line 750, in is_whitelisted
    throw(_("Not permitted"), PermissionError)
  File "apps/frappe/frappe/", line 504, in throw
  File "apps/frappe/frappe/", line 479, in msgprint
  File "apps/frappe/frappe/", line 434, in _raise_exception
    raise raise_exception(msg)
frappe.exceptions.PermissionError: Not permitted

this is permission error, and it does not come when this form is submitted after login.

Is there any way I could send SMS on WebForm submission without logging in to erpnext?

my code to send the SMS is below

frappe.web_form.after_save = () => {{
   method: "frappe.core.doctype.sms_settings.sms_settings.send_sms",
   args: {
       receiver_list: [number],
       msg: message,
   callback: function(r) {
       if (r.exc) {