Pretty sure the Intel modem in my iPhone X works just fine ...
It does so
only because it implements (and/or can implement with the right code) the IP developed by dozens of other companies.
That's why any device maker using any modem chip has to pay royalties to Qualcomm, Motorola, Nokia, Ericsson, LG, Samsung and many others who contributed inventions towards the standards that the modem chip makes use of.
The same rule applies to modem chips made by Qualcomm, of course. Royalties have to be paid by the phone maker to
all of the same IP holders. Do you get it now?
Who makes the chip itself does not matter. Intel, Qualcomm, MediaTek, Huawei, it makes no difference. They're only supplying the silicon, not the methods of using that silicon.
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Moreover, in this case you really picked a bad chip maker example, because the Intel modem silicon is ALSO in debt to Qualcomm's
non-FRAND chip implementation IP.
You see, Intel did not implement the CDMA standards from scratch. Instead, they bought a core Qualcomm licensed chip design enhanced by others. Intel bought this third party work in order to save years of startup modem R&D, just like how they bought Infineon for its GSM design. In short, even part of Intel's silicon was originally designed by Qualcomm.
