Apple used a newer generation of Samsung's CPU used in the iPod to develop both the iPod Touch as well as the iPhone, both introduced in 2007.
That's also a reason why the iPhone was not designed around a more power-efficient SoC which combined the CPU and the cellular Modem into one package: The Modem was the add-on to the architecture which turned the iPod Touch into that exclusive Phone they built for AT&T.
> Apple used a newer generation of Samsung's CPU used in the iPod
I mean, that's true only in the same way as your phone uses a newer generation of the CPU in your washing machine (these days, both are likely to contain ARM cores of some sort). They were both ARM SoCs made by Samsung, but the relationship kind of ends there; totally different ARM core, totally different peripherals, totally different everything.
That's not what I'm saying. They developed the next generation iPod on the next generation of their iPod CPU supplier platform. And then they added a modem and made it a phone.
They literally utilized their existing iPod supply chain to build the core BOM of the product.
That's also a reason why the iPhone was not designed around a more power-efficient SoC which combined the CPU and the cellular Modem into one package: The Modem was the add-on to the architecture which turned the iPod Touch into that exclusive Phone they built for AT&T.