Pore over periods announced to obtain reduced-price tickets (11)

I believe the answer is:

concessions

I'm a little stuck... Click here to teach me more about this clue!

'tickets' is the definition.
The definition and answer can be both related to communication as well as being plural nouns.
Maybe they are linked in a way I don't understand?

'pore over periods announced to obtain reduced-price' is the wordplay.
I cannot really see how this works, but
'over' could be 'on' (I've seen this in other clues) and 'on' is found in the answer.
This explanation may well be incorrect...

Can you help me to learn more?

I've seen this clue in The Telegraph.

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