This card seems pretty mediocre at first glance. 3 effective resources for 3 total attack/thwart. But after using it, this has quickly become one of my favorite cards. Where it really shines is in multiplayer. The main benefit to Cell Phone is not the extra stats, it's the ability to attack or thwart with a character out of turn. This card is so flexible and can be useful in many situations:
1) I want to attack the villain but they have tough, call on my teammate who has wolverine to pierce the tough first.
2) I want to hit the villain with spinning web kick but there's a pesky guard minion, call on my teammate to clear it with their hero.
3) I play Professor X, but my Magik teammate already confused the villain. X can ready her, and then give her a call to activate again on my turn.
4) We clear Call for Backup or I use Mutant Mayhem, but my teammate already took their turn. This will let them use that ally on this turn.
5) Playing with decks that rely on hitting big numbers (Overwatch, Moment of Triumph etc)