This code snippet shows how you might set a device to boot (warm or cold) into an offline state.

offlineStart.device.nut

// Set the reconnection policy as early as possible in the code
server.setsendtimeoutpolicy(RETURN_ON_ERROR, WAIT_TIL_SENT, 30.0);

// Disable the BlinkUp LED (enforced 60s after boot)
imp.enableblinkup(false);

local willNeedBlinkupFlag = false;
local netData = imp.net.info();

if ("active" in netData) {
    local interface = netData.interface[netData.active];
    if (interface.ssid == "") {
        // imp-enabled device is not configured for WiFi, so it can’t currently connect.
        // Record the fact there is no configuration in case we need to know later
        willNeedBlinkupFlag = true;
    } else {
        // imp-enabled device is configured for WiFi, so manually disconnect
        // when the device and impOS go idle
        imp.onidle(function() {
            server.flush(10);
            server.disconnect();
        });
    }
}