Apple's is still facing challenges in its bid to develop in-house modem chips.

According to Bloomberg's Mark Gurman, "the complexity of replacing an intricate Qualcomm component" means Apple's plan to make its own modem probably won't happen until late 2025 or early 2026. That's cutting it close for the current end of Apple's deal with Qualcomm, which will supply Apple with Snapdragon 5G modems for iPhones until 2026.

This comes after a September report from The Wall Street Journal, which called Apple's efforts to develop its own modem chip a "spectacular failure." Among the issues cited by the Journal is the need to make a chip that works with wireless networks around the globe.

Gurman suggests Apple "remains years away from cracking the problem," despite the company aggressively hiring from Qualcomm and purchasing Intel's modem business.

Apple was reportedly looking to debut its modem chip in an update to the lower-profile iPhone SE next year, but later pushed that to 2025 and might now have to wait until 2026, Gurman says.

Qualcomm says it's "planning as if we’re going to get 20% share" of Apple's modem chips come 2026." Any more than that is an "upside," says Qualcomm CFO Akash Palkhiwala, Bloomberg reports. In other words, Qualcomm understands that Apple might ship its own chips in 2026, but if not, Qualcomm is ready to supply more.

Another Qualcomm-related concern: Don't rock the boat when it comes to patents. The two companies settled a long-running patent dispute in 2019, but Qualcomm will surely be on the lookout for any parts of Apple's new modem that infringes on its patents, Gurman notes.