I read this while up at my grandparents somewhere around 1990ish. Given how many books they had from when my dad was growing up, there's a decent chance that it's older. It was a novel where the government kept pretty strict control of society. They had some sort of mass entertainment covered because I remember a reference to the government giving the citizens "their bread and circuses" as a reference to the Roman practices. The biggish twist is that the resistance isn't so much actively fighting the government as that they're producing a pressure valve by using their hackers to set up telephone relays which act as support lines. Anyone can call and talk about their troubles. The telephone technology was relatively old — I think I remember them talking about mechanical relays — and they advertised the changing numbers (they had to keep going to new ones as the government shut down the old ones) on flyers that they posted all over the place.
The one bit of imagery that really stuck out to me was where a female member of the resistance was explaining to the male protagonist that, no matter how bad things got, they had to stay on the line, and she recounted one of her first calls involving a mother who'd locked her baby into a high-chair and was flinging spoonfuls of vitriol (acid, but they specifically used the word "vitriol") at the baby as she talked.
I don't think I ever got to finish the book, so I have no idea how it ended.