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

Verizon New

Verizon is Down: iPhones Show 'SOS' Mode Due to Network Outage [Resolved]

Wednesday January 14, 2026 10:18 am PST by
Verizon is experiencing a major outage across the U.S. today, with hundreds of thousands of customers reporting issues with the network on the website Downdetector. There are also complaints across Reddit and other social media platforms. iPhone users and others with Verizon service are generally unable to make phone calls, send text messages, or use data over 5G or LTE due to the outage....
Apple Creator Studio

Apple Introduces New 'Creator Studio' Bundle of Apps for $129 Per Year

Tuesday January 13, 2026 6:11 am PST by
Apple today introduced a new Apple Creator Studio bundle that offers access to six creative apps, as well as exclusive AI features and content, as part of a single subscription. In the U.S., pricing is set at $12.99 per month or $129 per year. Here are the six apps included with an Apple Creator Studio subscription:Final Cut Pro on the Mac and iPad Logic Pro on the Mac and iPad Pixelmator...
iOS 26

Here's What's New in iOS 26.3 So Far

Monday January 12, 2026 1:15 pm PST by
Apple today seeded the second beta of iOS 26.3, nearly a month after the first beta. So far, the update includes a couple of new features for iPhones. iOS 15.3 through iOS 18.3 were all released in late January over the years, so it is thereby likely that iOS 26.3 will be released towards the end of this month as well. The update is compatible with the iPhone 11 series and newer. Below,...
maxresdefault

Apple Confirms Google Gemini Will Power Next-Generation Siri This Year

Monday January 12, 2026 7:38 am PST by
In a statement shared with CNBC today, Apple confirmed that Google Gemini will power the next-generation version of Siri that is slated to launch later this year. Subscribe to the MacRumors YouTube channel for more videos. "After careful evaluation, we determined that Google's technology provides the most capable foundation for Apple Foundation Models and we're excited about the innovative...
airpods pro 3 design

Apple Releases New AirPods Pro 3 Firmware Update

Tuesday January 13, 2026 11:29 am PST by
Apple today released a firmware update for the AirPods Pro 3. The latest firmware has a version number of 8B34, up from the previous version 8B30. Apple has a support document for AirPods firmware updates, and it indicates that the 8B34 update contains unspecified "bug fixes and other improvements." No other AirPods models received firmware updates today. How to install AirPods Pro...
Low Cost MacBook Feature A18 Pro

Apple Is Expected to Launch These Four MacBooks in 2026

Friday January 9, 2026 8:17 am PST by
2026 could be a bumper year for Apple's Mac lineup, with the company expected to announce as many as four separate MacBook launches. Rumors suggest Apple will court both ends of the consumer spectrum, with more affordable options for students and feature-rich premium lines for users that seek the highest specifications from a laptop. Subscribe to the MacRumors YouTube channel for more videos. ...
maxresdefault

Google Gemini-Powered Siri Will Reportedly Have These 7 New Features

Tuesday January 13, 2026 7:52 pm PST by
Apple and Google this week announced that Gemini will help power a more personalized Siri, and The Information has provided more details. Subscribe to the MacRumors YouTube channel for more videos. As soon as this spring, the report said the revamped version of Siri will be able to… Answer more factual/world knowledge questions in a conversational manner Tell more stories Provide...
fcp pcp iwork creator studio

Some Apple Apps Will No Longer Receive Every New Feature Without a Subscription

Tuesday January 13, 2026 10:50 am PST by
If you are not interested in subscribing to the new Apple Creator Studio bundle introduced today, you will officially start to miss out on some new features. Apple said some "exciting new intelligent features and premium content" in Pixelmator Pro, Keynote, Numbers, Pages, and Freeform will only be accessible with a Creator Studio subscription. In the U.S., a subscription costs $12.99 per...
iPhone Top Left Hole Punch Face ID Feature Purple

New Leak Reveals iPhone 18 Pro Display Sizes, Under-Screen Face ID, and More

Wednesday January 14, 2026 7:09 am PST by
While the iPhone 18 Pro models are still around nine months away, a leaker has shared some alleged details about the devices. In a post on Chinese social media platform Weibo this week, the account Digital Chat Station said the iPhone 18 Pro and iPhone 18 Pro Max will have the same 6.3-inch and 6.9-inch display sizes as the iPhone 17 Pro and iPhone 17 Pro Max. Consistent with previous...
iPhone Top Left Hole Punch Face ID Feature Purple

10 Reasons to Wait for This Year's iPhone 18 Pro

Thursday January 8, 2026 2:56 am PST by
Apple's iPhone development roadmap runs several years into the future and the company is continually working with suppliers on several successive iPhone models at the same time, which is why we often get rumored features months ahead of launch. The iPhone 18 series is no different, and we already have a good idea of what to expect for the iPhone 18 Pro and iPhone 18 Pro Max. One thing worth...

Top Rated Comments

Jmausmuc Avatar
68 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
68 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
68 months ago
Are you kidding me?!

i will cancel my order of this is true.
Score: 17 Votes (Like | Disagree)
phatspider Avatar
68 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
68 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
68 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)