How long generally, or specifically on 2Degrees.  Might an SMS exist if there's nothing currently up to receive it?

I've got a gps tracker, that until recently was on azue.  I'm pulling it home.  But part of that is that the device needs an ip address to talk to, it can't use a dns name (BOOOO).

So the question is, if I change my IP address (router reboot or something) and fire off a text with my new ip address - how long will that sms try to deliver for if the device is not used every day.