Phones can only be used when you ask for cards, so the first sentence of the card should read:

Instead of your normal request, discard 3 Phones to ask another player if they have specific cards without revealing those cards.

To clarify: You may not ask for more cards than you have remaining in your hand after you discard the Phones.

Tip: One of the only ways to get a pair of special cards from someone else is to use the Phones. Also, if you just checked someone’s hand, you can use the Phones to ask for a bunch of cards from it on your next turn … as long as you remember the cards correctly!