Just make sure you use it for a few days before hand so it doesn't appear to be a burner phone, lest you be considered suspicious and remanded for additional interrogation.
Wouldn't they notice all your mail, call list, and other such accounts are from a few days?
No need to bother.
Most companies of any size, and us civil servants, have policies to travel with burner phones/laptops when crossing (even some benign) international boarders and/or entering certain countries.
Frankly, it is so commonplace, it is not remotely suspicious to travel with a burner.