The landline isn’t dead yet (not that I’m foreseeing a comeback). If you need a little something to tide you over during the death throes, there’s the Home Phone and iPhone Unifier.
It’s a dock for both a cordless landline phone and an iPhone, and enables you to use both interchangeably. The cordless handset included with the set can communicate with your iPhone via Bluetooth, so you can take calls on one or the other, regardless of whether you’re receiving a call to your landline or mobile number. About 1,000 contacts can be imported to the landline handset from your iPhone, too.
I’m not sure what the advantage here is, or, if there is an advantage, that it will necessarily pay for the cost of the unit, but if you think the Home Phone and iPhone Unifier can carve out a niche in your life, it’s available now on Hammacher Schlemmer for $200. The dock is designed for 30-pin connector iOS devices, so you won’t be able to charge your iPhone 5 using this dock without an adapter. You will be able to use the iPhone 5 for the Bluetooth call pairing feature.