Why I Like Duopoly

Our telecom bill is huge; for cable (no premium channels), cable modem, landline, and my iPhone, it’s about $250. I’ve tried to get AT&T to give me a deal on the landline and iPhone, but to no avail.
The cable company, however, will take over my landline at a total price for everything but the iPhone at $5 more than I now pay for the cable and modem alone. Admittedly, this is an introductory rate, but it rises by only $10 after one year.
I don’t like duopoly, but it’s better for me the consumer than a monopoly; and there are other threats — satellite TV, for example — that limit pricing even more. How can the cable company offer me a price for all the cable services only $5 above my current price? Easy — the marginal cost to them is tiny. The cable service is already there; but if I switched cable service to AT&T, they would lose a lot. This is a good move for them. I only wish I had switched earlier.