My take is similar to Tyoka's, but depends on the power level of the telepath... telepathy granted by a high-level spell or possessed by a high-CR creature would be more likely to allow the user to "hear" thoughts that weren't directly sent to them.
I would give higher-power telepathy the ability to act like spoken language, but with thoughts... if someone in your telepathy range thought your name, or something important that you're seeking information on, that thought would be heard, along with the next couple thought words after it... kind of like when you're in a crowd of people conversing, and you suddenly hear someone say your name, and you hear the next couple words after it as well once you're "focused in" on the speaker after the "cue". Could lead to, "Hey, what were you just thinking about me?" moments. :P