I'd assuming they're talking about TETRA, presumably one of the export versions (I don't think TEA2 (only available to European public safety orgs) is known to be broken at this point, though its age and obscure nature wouldn't give you much confidence).
Their implementation added one more round of encryption for unknown reasons, which turns out weakened AES enough to break it with a GPU cluster. Google looks to be well scrubbed of the story but it featured on HN a while back.
There's a good talk on it here: https://media.ccc.de/v/37c3-11761-all_cops_are_broadcasting