iPhone 12 Models in Dual SIM Mode May Not Run at 5G Speeds, At Least Initially [Update: Confirmed]

Using an iPhone 12 in Dual SIM mode throttles the cellular data speed to 4G LTE, according to an Apple Sales FAQ shared with retailers and carriers.

Screen Shot 4
All 5G iPhone 12 models support Dual SIM mode, which refers to the ability to switch between a SIM card and an eSIM operating on independent numbers and/or carriers. However, an image of a training document from Apple's Sales Web resources called "What you need to know about 5G on ‌iPhone‌" and posted to Reddit suggests the ‌iPhone‌ 12 will not support 5G on either line when Dual SIM mode is active. The FAQ reads:

"Does 5G work with Dual SIM?"
When using two lines in Dual SIM mode, 5G data isn't supported on either line and will fall back to 4G LTE. If customers are using eSIM only and are on a 5G-supported carrier and service plan, they'll have 5G access.

The document suggests that only by disabling one SIM or the other will 5G speeds be available – a limitation that, if confirmed, will come as a blow to ‌iPhone‌ 12 customers who intended to use separate work and personal lines, for example.

5G dual sim incompatible
On the bright side, this incompatibility could be a software issue, and therefore something Apple could resolve down the line. Indeed, the Reddit user who posted the above image claims that an update coming later in 2020 will enable 5G when using a Dual SIM mode.

This information is allegedly revealed in Apple's internal training documents, but 5G is not anywhere mentioned in Apple's Dual SIM support page, which was last updated on September 26. We've reached out to Apple to clarify the matter and will update this article if we get a response.

(Thanks, De Paul Sunny!)

Update: MacRumors has received independent confirmation that the documentation is genuine.

Tags: 5G, eSIM
Related Forum: iPhone

Popular Stories

iPhone 17 Pro 34ths Perspective

iPhone 17 Pro Launching Later This Year With These 10 New Features

Sunday March 23, 2025 10:00 am PDT by
While the iPhone 17 Pro and iPhone 17 Pro Max are not expected to launch until September, there are already plenty of rumors about the devices. Below, we recap key changes rumored for the iPhone 17 Pro models as of March 2025: Aluminum frame: iPhone 17 Pro models are rumored to have an aluminum frame, whereas the iPhone 15 Pro and iPhone 16 Pro models have a titanium frame, and the iPhone ...
Generic iOS 18

iOS 18.4 Coming Soon With These New Features for Your iPhone

Tuesday March 25, 2025 6:45 am PDT by
Apple is expected to release iOS 18.4 to the general public as soon as next week, following more than a month of beta testing. Apple's website says some iOS 18.4 features will be released in "early April," so the update should be out as early as Tuesday, April 1. Apple this week seeded the iOS 18.4 Release Candidate, which is typically the final beta version, barring the discovery of any...
ios 19 messages app

Here's What Apple's iOS 19 Messages App Might Look Like

Tuesday March 25, 2025 11:52 am PDT by
Leaker Jon Prosser today shared a mockup of what he says the Messages app will look like in iOS 19, demoing an interface with rounded, translucent bubble-shaped navigation buttons at the top and softer, rounder corners for the keyboard and word suggestions. Jon Prosser's Messages app mockup The return button, a button for going back to the Messages list, and the FaceTime button have a deeper...
iCloud General Feature Redux

iPhone Users Who Pay for iCloud Storage Receive a New Perk

Thursday March 20, 2025 12:01 am PDT by
If you pay for iCloud storage on your iPhone, Apple has a new perk for you, at no additional cost. The new perk is the ability to create invitations in the Apple Invites app for the iPhone, which launched in the App Store last month. In the Apple Invites app, iCloud+ subscribers can create invitations for any occasion, such as birthday parties, graduations, baby showers, and more. Anyone ...
macbook pro blue green

When Will Apple Release the M5 MacBook Pro?

Wednesday March 26, 2025 4:53 pm PDT by
Apple regularly refreshes the MacBook Pro models, and a new version that uses M5 series chips is in the works. Apple just finished refreshing most of the Mac lineup with M4 chips, and now it's time for the M5. Rumors suggest that we could see the first M5 MacBook Pro models this fall. Design There have been no rumors of a design update for the M5 MacBook Pro models that are coming this...
airpods max 2024 colors

Don't Buy Into Apple's Hype About AirPods Max Gaining Lossless Audio

Monday March 24, 2025 4:24 pm PDT by
Apple today announced that AirPods Max with a USB-C port will be gaining support for lossless audio and ultra-low latency audio with a firmware update next month, alongside the release of iOS 18.4, iPadOS 18.4, and macOS 15.4. For context, audio files are typically compressed to keep file sizes smaller. There are lossy compression standards like MP3 and AAC (Advanced Audio Codec), which...
Apple Lumon Terminal Pro

Apple's Mac Site Features Fictional 'Lumon Terminal Pro'

Wednesday March 26, 2025 12:19 pm PDT by
Apple is going all out with promotions for the popular Severance Apple TV+ show today, and as of right now, you'll find a new "Lumon Terminal Pro" listed on Apple's Mac site. The Lumon Terminal Pro is designed to look similar to the machines that Severance employees like Mark S. and Helly R. use for macrodata refinement. The Terminal features a blue keyboard, a small display with wide...
Generic iOS 19 Feature Mock

Gurman: Jon Prosser's iOS 19 Mockups 'Aren't Representative' of Redesign

Tuesday March 25, 2025 4:47 pm PDT by
The iOS 19 mockup images that leaker Jon Prosser shared today are not representative of the actual iOS 19 design, Bloomberg's Mark Gurman said on social media. According to Gurman, the images that are "floating around" are based on "very old builds" or "vague descriptions," and are lacking key features. Gurman says that we can "expect more from Apple in June." Gurman made the same comment ...

Top Rated Comments

Jmausmuc Avatar
58 months ago

Here comes the “power users” that must have the already sparse 5G coverage at all times. ?

I personally use dual sim for international travel, it is a non-issue.

And of course... we will have many that claim it is a “deal breaker”
Good for you. I use dual sim 24/7 for work so the biggest feature of the iPhone 12 won’t work for me at all.
I have the right to be disappointed.
Score: 26 Votes (Like | Disagree)
Malus120 Avatar
58 months ago
That's pretty unacceptable if true, and if its unfixable is likely to be a deal breaker for a small but important minority of power users (myself included).

If this is anything more than just an initial software bug (AKA if this is a hardware limitation) I really have to question whether or not the iPhone 12 is ready for prime time.
Score: 19 Votes (Like | Disagree)
Jmausmuc Avatar
58 months ago
Are you kidding me?!

i will cancel my order of this is true.
Score: 17 Votes (Like | Disagree)
phatspider Avatar
58 months ago

Ok... show me show Sidney is blanketed in 5G... today
I assume you mean Sydney. Here is one of the 3 networks for this little village.
Covers where i live, work, run, drink, gym, BJJ and where 99% of my friends live.
Next?

Attachment Image
Score: 14 Votes (Like | Disagree)
Jmausmuc Avatar
58 months ago
Order is now cancelled, sticking with XS for another year. Disappointing because I was looking forward to some new tech, but since I don’t take many pictures, the iPhone 12 already felt like only a smalll update.

i would not be able to use 5G at all, because I use dual sim 24/7.

I am waiting for the next iPhone with hopefully real 5G (including international UW) support, 120hz and a smaller notch. That will feel much better
Score: 13 Votes (Like | Disagree)
phatspider Avatar
58 months ago

Ok.. show me the uk map of 5G...
Erm what again. Did you really think Sydney was in the UK? Cute.
There’s 193 other countries other than US and UK
Score: 13 Votes (Like | Disagree)