Having never owned any cell phones but burners, I am not sufficiently familiar with the tech to know exactly how they work. I know you can't use them with gloves on, but I think you can use a stylus on them, so I don't know how much body heat comes into it. They're the only undead that I can think might be interested in using phones (maybe the Arnold Vosloo mummy, but IDK what the body temp rules for him are anyway), so there are not any available cross-references I can think of.

Any thoughts?