Device.ondisconnect how to identify the device when running on multiple imps?

Hello i have 3 imps devices with the same code. When one does down i have this code but how do i identify in the sms sent what device is down ?

device.ondisconnect(function() {
local url = “https://rest.nexmo.com/sms/json
local apiKey = “xxx”
local apiSecret = “xxx9”
local fromNumber = “xxx”
local toNumber = “xxxxxx788560”
local message = “IMP - B3 disconected”

local payload = {
  "api_key": apiKey,
  "api_secret": apiSecret,
  "from": fromNumber,
  "to": toNumber,
  "text": message
}

local request = http.post(url, { "Content-Type": "application/json" }, http.jsonencode(payload))

request.sendasync(function(response) {
  if (response.statuscode == 200) {
    server.log(response.body)
  } else {
    server.error("Error:", response.body)
  }
})   

});

You could have the device call hardware.getdeviceid(), forward that with agent.send() when it first connects and then append it to your message.