I'm in Johannesburg but moving to Cape Town in 3 months where it will be the same.
I don't need or use the phone. I am on Vodacom (cellphone) for that.
At home, 4Mb dialled down to 2Mb (distance from exchange)
Primary use for the voice capability is troubleshooting - listening for impulse noise, buzz due to line problems.
I also have many clients that I've set up to do the same. Paying for something you don't need or want is unfair... with out voice means we can afford to up the line speed.