Attempts to connect to the Cellular network. If there are no credentials entered, the default Particle APN for Particle SIM cards will be used. If no SIM card is inserted, the device will enter listening mode. If a 3rd party APN is set, these credentials must match the inserted SIM card for the device to connect to the cellular network. When this function returns, the device may not have a local (private) IP address; use Cellular.ready() to determine the connection status.


On Gen 3 devices (Argon, Boron, B-Series SoM, and Tracker), prior to Device OS 2.0.0, you needed to call WiFi.on() or Cellular.on() before calling Particle.connect(). This is not necessary on Gen 2 devices (any Device OS version) or with 2.0.0 and later.