Player > Feats > Telepathic Spy
Your telepathy is sensitive enough to detect similar psychic communication nearby.
Limited telepathy or telepathy.
When a creature within range of your telepathy uses telepathy, receives telepathic communication (such as telepathic message), or employs a mind-reading effect (such as the detect thoughts spell), you notice the attempt with a successful DC 20 Sense Motive check. If you succeed by 5 or more, you glean three pieces of information about the communication, such as the identity of its source, its general nature, the emotional state of the sender or the recipient, and so on. If you succeed by 10 or more, you can listen in on the communication by concentrating each round (a standard action) to maintain your eavesdropping. However, although unaware of your spying, the subject can attempt a saving throw (DC = 10 + half your level + your Charisma modifier) to prevent it. Succeeding by 5 or more at this save also alerts the subject to your snooping.