actually licensing a modem is not the solution even if you could do it. the problem is getting the ip ported to your process. most existing ip is designed and verified for the tsmc, umc, charted etc. these foundries have an extensive end-user library generation, shuttle and assembly/testing support. if intel wants anyone to port their ip to its fabs, it has to support all of these. i think they have learned a great deal through their achronix, altera, tabula partners but i am still not sure whether they are ready for the smaller ip vendors who don't make their own chips. buying the ip (vendor) and getting it to work on your process is probably the better way to go and this they did. they bought quite a bit of modem companies but still converting parts of it to your fab and producing the rf at another fab is difficult.
one reason intel has an overwhelming process for their cpus is that the process is optimized for the chip and the chip is optimized for the process. this is not a good recipe for off-the-shelf ip.