Apple sells the iPhone Duo in four versions: A3447 in the United States, A3719 in Japan, Canada, Mexico and the Gulf, A3720 in 190 other countries, and A3721 in China mainland. They look identical and all four are eSIM-only, but Apple lists a different set of cellular bands for each, and only one of them can hold a China mainland carrier eSIM.
The differences are small for most travellers and decisive for a few. The US version is the only one Apple lists with 5G mmWave. The version sold in Japan, Canada and the Gulf carries the longest LTE list. The 190-country version is the one most buyers outside those markets get. Here is what each A-number means, and how to check which one is in your hand.
- A3447: United States and Puerto Rico. 29 5G bands, the only list with mmWave.
- A3719: 11 markets including Japan, Canada, Mexico, Saudi Arabia and the UAE. 33 LTE bands, the longest list.
- A3720: 190 countries, including the UK, Germany, Australia, Hong Kong, India and Singapore.
- A3721: China mainland only, and the only version that can install a mainland carrier eSIM.
- Every version: eSIM-only. There is no iPhone Duo with a SIM tray.
The four iPhone Duo versions
Apple publishes the sales regions and supported bands for every model number on its cellular page. This is that page, condensed.
| Model | Where Apple sells it | 5G bands | LTE bands | mmWave |
|---|---|---|---|---|
| A3447 | United States, Puerto Rico | 29 | 31 | Yes: n258, n260, n261 |
| A3719 | Japan, Canada, Mexico, Guam, USVI, Bahrain, Kuwait, Oman, Qatar, Saudi Arabia, UAE | 26 | 33 | No |
| A3720 | 190 countries, including the UK, Germany, Australia, Hong Kong, Macao, India, Singapore and South Korea | 23 | 28 | No |
| A3721 | China mainland | 22 | 27 | No |
The band lists nest neatly. A3447 has everything A3720 has, plus n14, n29, n71 and the three mmWave bands. A3719 has everything A3720 has, plus n14, n29 and n71 on 5G and bands 11, 14, 21, 29 and 71 on LTE. A3721 is A3720 minus n53 and LTE band 53. Nothing on the global version is missing from the US or Japan versions.
What the differences actually change
mmWave, on the US version only. Apple lists n258, n260 and n261 for A3447 and for no other iPhone Duo. mmWave is a short-range, high-capacity flavour of 5G that carriers deploy in limited places such as stadiums and dense city blocks. A US Duo can use it where a carrier offers it; the other versions are not built for it. For everyday travel data, the sub-6 bands below do the work.
The extra bands on A3719 and A3447. Bands n14, n29 and n71, and LTE 11, 14, 21 and 29, are used in specific markets, mostly North America and Japan. That is why Apple ships a version carrying them to those regions. Taking an A3720 to Japan or the US is not a problem in itself, but the phone will not use bands it does not support.
The China mainland version. A3721 drops n53 and LTE 53, and gains something no other version has: Apple says it can install an eSIM profile from China Mobile, China Telecom or China Unicom. Every other iPhone Duo, including one bought in Hong Kong, cannot. Our guide to iPhone Duo in China and Hong Kong covers that rule in detail.
What does not differ: all four are eSIM-only, all four hold two active eSIMs, and all four take a travel eSIM from a worldwide provider in the ordinary way. The one exception, again, is the mainland version, which Apple says stores two eSIMs rather than eight or more.
How to check which iPhone Duo you have
- On the phone: Settings, General, About. Look at Model Number. If it shows a part number, which starts with M, tap it once to reveal the A-number.
- On the box: the tech specs label on the back of the retail packaging carries the model number.
- Do not go by the name. “iPhone Duo” is the same name in every market. The A-number is what tells you which version you have.
- Buying second-hand: ask for the A-number and the Carrier Lock line from the About screen before paying.
The same exercise is worth doing on any iPhone bought abroad. Our iPhone 18 Pro model numbers guide covers the Pro line, and the SIM tray by country guide covers which versions still have a tray. On the Duo the answer is short: none of them.
Does the version matter when you travel?
For most trips, no. The 190-country A3720 supports the bands used across Europe, Asia-Pacific and most of the world, and a travel eSIM runs on those networks like any other line. Where the version shows up is at the edges: a global Duo in the United States will not use mmWave, and an American Duo in China mainland cannot hold a mainland carrier eSIM.
Band support is also not a service guarantee. Which frequencies a network actually uses in a given city, which ones a roaming agreement covers, and how the local carrier configures its cells all sit outside Apple’s list. We have not tested any of these versions on the ground.
Because every iPhone Duo is eSIM-only, the practical travel question is not which bands you have but whether you have a plan before you land. Apple’s travel guidance notes that worldwide providers offer prepaid data eSIMs, including for visitors to China mainland, and installing one needs an internet connection, so do it at home.
Travelling with an iPhone Duo? Browse travel eSIM plans for 190+ destinations, or go straight to Japan, the US, China or Europe. Our eSIM-only travel guide for iPhone Duo walks through the setup.
Sources
Model numbers, sales regions and band lists come from Apple’s iPhone cellular page, read on 19 September 2026. The SIM line is from Apple’s iPhone Duo tech specs. The China mainland eSIM rules are from Apple’s support article on using eSIM in China mainland, published 9 September 2026. Counts in the table are of the bands Apple lists for each model; Apple can change model numbers, regions and bands at any time.
Frequently asked questions
What is the iPhone Duo model number?
There are four. Apple lists A3447 for the United States and Puerto Rico, A3719 for Japan, Canada, Mexico and several Gulf markets, A3720 for 190 other countries, and A3721 for China mainland. Check yours in Settings, General, About.
Which iPhone Duo model is sold in the UK and Europe?
A3720, the version Apple lists for 190 countries, which also covers Australia, Hong Kong, Macao, India, Singapore and South Korea. Apple lists 23 5G bands and 28 LTE bands for it, without mmWave. It is the version most buyers outside North America, Japan, the Gulf and China receive.
Does the US iPhone Duo work abroad?
Apple lists every band for A3447 that it lists for the global A3720, plus mmWave and three more. Bands are not a service guarantee, but on paper a US Duo is not missing frequencies the global version has.
Which iPhone Duo supports mmWave 5G?
Only A3447, the United States and Puerto Rico version. Apple lists n258, n260 and n261 for it and for no other iPhone Duo. mmWave is deployed in limited areas, so most travel data runs on sub-6 bands anyway.
Does the China mainland iPhone Duo differ?
Yes. A3721 is the only version that can install an eSIM from China Mobile, China Telecom or China Unicom, activated in person at a carrier store. Apple also says a mainland iPhone stores two eSIMs rather than eight or more.
Does any iPhone Duo have a SIM card slot?
No. Apple lists iPhone Duo as dual eSIM in every market and says it is not compatible with physical SIM cards. If you need a physical nano-SIM, look at iPhone 18 Pro, iPhone 18 Pro Max or iPhone 17 instead.
How do I find my iPhone Duo A-number?
Open Settings, General, About and look at Model Number. If it shows a part number, tap it once and the A-number appears. The retail box also carries the model number on its tech specs label.
Do I need a specific iPhone Duo version for a travel eSIM?
No. All four versions take an eSIM from a worldwide provider in the same way, and all four hold two active eSIMs. The only version-specific rule is in China mainland, where only the mainland A3721 can install a local carrier’s eSIM profile.
Bottom line
Four iPhone Duo versions, and for most travellers the choice barely matters: the global A3720 covers 190 countries and runs a travel eSIM exactly like the rest. The two cases worth knowing are mmWave, which Apple lists only on the American A3447, and China mainland, where only A3721 can hold a local carrier’s eSIM. Check your A-number in Settings before you shop, and remember that every Duo is eSIM-only.
Last reviewed 19 September 2026. Model numbers, regions and bands are from Apple’s cellular page and iPhone Duo tech specs, read on that date, and can change at any time. Band support describes the hardware, not network availability. Apple and iPhone are trademarks of Apple Inc.; this article is independent editorial commentary and is not affiliated with, sponsored by or endorsed by Apple. Illustrations are our own.