You are allowed to use TS. It is not wise (many do which if fine) to use teamspeak during a situation as it has a tendency to take away from the overall situation/experience especially for the hostage(s).
I joined not few days ago so i had to read carefully the rules, and actually it is a metagaming situation, wich is punishable, however it tend to be tolerated, but it ruin totally the immersion... "Metagaming is a broad term generally used to define any strategy, action or method used in a game which transcends a prescribed ruleset, uses external factors to affect the game or goes beyond the supposed limits or environment set by the game. Metagaming is when a player receives information that they otherwise should not have received in any reasonable role-play way." here are the rules about metagaming, and in the examples there is the sentence "Using information posted on the forums, acquired in TeamSpeak or any other similar way to your advantage." so technically it is a reportable attitude
I will not report it since the OP is new here, but definitly stop using Teamspeak alone in the game, or if you do so use "push to talk" button and use the same assignement that you use in the game