Do you equip your "backup spotter" with a walkie-talkie?

If she's with me, I send her off to take the dogs for a walk and I back in myself with frequent walks back to scope things out....I thought though, that rather than a walkie talkie, if she were to assist in some way (not holding my breath here) she could use her cell phone and as I've got bluetooth in my TV, I could just converse while backing...