The iPhone 17 Air is expected to be the second Apple smartphone to feature the home-brewed C1 modem. It will join the iPhone 16e, which was announced in late February. Network intelligence company Ookla published a report comparing the performance of the C1 modem with the Qualcomm modem found in the iPhone 16 to show us how they stack up against each other.
The C1 is a power-efficient modem, but it isn't equipped to tap into the highest speeds offered by carriers.
iPhone 17 Air might not be the right choice for US buyers
According to Ookla's analysis, the iPhone 16e performs similarly to the iPhone 16 in most markets. Where the iPhone 16 shines is the regions with advanced 5G standalone (SA) networks, as Qualcomm's modem can take better advantage of them. The C1 modem in the iPhone 16e doesn't offer the same level of performance because it's held back by its specs.
This means that in countries with capable 5G networks, such as the US, China, India, and Saudi Arabia, the iPhone 16 generally performs better than the iPhone 16e.
Better download speeds on iPhone 16 for T-Mobile and Verizon users
The iPhone 16 provides better download speeds than the iPhone 16e. | Image Credit - Ookla
T-Mobile and Verizon customers experience better media download speeds on the iPhone 16. T-Mobile users achieved a median download speed of 317.64 Mbps, while Verizon users logged a median download speed of 172.12 Mbps.
The difference is seemingly so pronounced because T-Mobile is the only carrier to have a nationwide 5G SA network and has deployed advanced features such as carrier aggregation.
The company used four-carrier aggregation across more than 65 percent of its network during the first half of the year. T-Mobile will only expand the use of the spectrum-combining tech, so the iPhone's performance will improve over time.
The size of the carriers being aggregated also matters. T-Mobile combines 217 MHz of spectrum.
AT&T mostly uses two-carrier aggregation, which both the iPhone 16 and 16e can take advantage of. It combines 120 MHz on average. Verizon is ramping up the use of two-carrier aggregation and moving toward three-carrier aggregation. It utilizes 170 MHz.
This explains why T-Mobile offers the fastest download speeds for someone with the iPhone 16.
Qualcomm's latest flagship modems, the X80 and X85 modems, support 6-carrier aggregation for downloads and can work with more spectrum. The Samsung Galaxy S25 uses the Snapdragon X80 5G modem, so we wouldn't be surprised to see it inside all the upcoming iPhone 17 models, except the iPhone 17 Air.
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The C1, on the other hand, only supports 3-carrier aggregation for downloads.
The X80 and X85 also support uplink carrier aggregation and uplink MIMO, while the C1 does not. This means that the phones with Qualcomm's recent modems will enjoy faster upload speeds and better capacity than the C1 iPhones.
Upload speeds
Upload speeds are better on iPhone 16e for AT&T and Verizon customers. | Image Credit - Ookla
In countries with cutting-edge networks, the iPhone 16 outperforms the 16e in upload speeds, though the reverse is true in the US, but not for all carriers.
On Verizon and AT&T, the iPhone 16e provides better upload speeds, but on T-Mobile, they perform similarly.
Is network performance something you consider when buying phones?
No. I don't care because I mostly use WiFi.
22.73%
No, but I will after today.
4.55%
Yes.
72.73%
One area where the iPhone 16e has a clear lead is for users who generally experience weak network performance due to factors such as distance from a cell tower or congestion. The iPhone 16e provides better performance in such situations, apparently because many of the users who typically get low speeds are connected to low-band 5G, which is slow but penetrates deeper. During these times, Qualcomm's modem isn't able to flex its muscles because there is no additional spectrum to combine.
That's especially true for AT&T and T-Mobile users, but less so for Verizon customers.
Unless you reside in an area with consistently low speeds, the iPhone 17 Air doesn't look like a safe bet if you are with T-Mobile. Of course, the speed metrics might not matter much if that's not your primary concern, or your need for a thin phone overrides everything else.
Even if you aren't a T-Mobile customer, given that Qualcomm's modems can take better advantage of advanced networks, you'd be better off with the iPhone 17, iPhone 17 Pro, or iPhone 17 Pro Max if your country has a capable 5G network.
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Anam Hamid is a computer scientist turned tech journalist who has a keen interest in the tech world, with a particular focus on smartphones and tablets. She has previously written for Android Headlines and has also been a ghostwriter for several tech and car publications. Anam is not a tech hoarder and believes in using her gadgets for as long as possible. She is concerned about smartphone addiction and its impact on future generations, but she also appreciates the convenience that phones have brought into our lives. Anam is excited about technological advancements like folding screens and under-display sensors, and she often wonders about the future of technology. She values the overall experience of a device more than its individual specs and admires companies that deliver durable, high-quality products. In her free time, Anam enjoys reading, scrolling through Reddit and Instagram, and occasionally refreshing her programming skills through tutorials.
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