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iOS 7 becomes first commercial software to support multipath TCP, allowing simultaneous Wi-Fi and cell network connections


It seems Apple included a bit of a networking surprise in iOS 7. According to a logs captured from an iOS device while connecting to Apple’s Siri servers, the latest version of the mobile operating system includes support for a new technology called multipath TCP. Multipath TCP allows devices to transmit data over multiple connection types at once, such as LTE, Wi-Fi, and Bluetooth.

Essentially, this allows devices to maintain their connection to the Internet or another device even if one of the connections fails. Say for example you were on a weak Wi-Fi network that kept cutting out while attempting to watch a YouTube video. On most Internet-connected devices, that video would stop loading when your connection died, and even if it quickly reestablish a connection by finding that weak Wi-Fi signal or switching to LTE, the device would have to reopen the connection to YouTube and start downloading the video again.

With MCTCP your iOS 7 device will be able to stay connected over both LTE and Wi-Fi at once. If your Wi-Fi connection fails, the LTE connection would continue downloading the data uninterrupted. You would likely never even know the difference unless you tapped the screen and checked your signal indicator.

iOS 7 is the first commercial software to ship with a working MCTCP implementation. The technology doesn’t require any special hardware, so existing devices will be able to take advantage of this feature, too.

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  1. Chris Allen - 10 years ago

    This sounds great – except most people use WiFi to try and avoid using their data too quickly.

    • That’s very true Chris.

    • standardpull - 10 years ago

      No. Your conclusion is wrong.

      Like today, your phone chooses wifi or cell for data xfer all on its own, with no intervention from you. But with MP, connections don’t get broken with switching. This means fewer partial xfers, higher efficiency (fewer chucked packets) and overall data savings.

      MP will save you time and data. Great thing.

  2. So, in the end, in spite you chose to connect to a WiFi to avoid charges, you’ll end up paying! No way to lose, companies are clapping all ready!

    • Nat Julian Belza - 10 years ago

      No. You can always choose to NOT use cellular data, just like before. This new feature will only work if you normally keep cell network ON. It doesn’t turn on cell data by itself unless you do.

    • mikhailt - 10 years ago

      So turn off the cell radio when you connect to the Wi-Fi network. This only switches once the connection to the Wi-Fi is lost. The point is that this allows for a smooth roll-over to a better connection without degrading the experience.

    • Grahame V Smith - 10 years ago

      The point is when working in the field often on critical applications continuity of singal might save time money even lives. It is a big deal and not to be viewed cynicaly.

  3. ivolgers - 10 years ago

    I like this but I do feel like this could be a HUGE battery drain. Going to wait and see.

    • mikhailt - 10 years ago

      Weaker Wi-Fi connection will drain the battery quicker than switching to a stronger LTE connection.

      It has to give more power to the radio to maintain the stability of the weak connection.

  4. kaeptnschneider - 10 years ago

    “You won’t see Multipath TCP for regular TCP connections from applications like Safari, but if you use SIRI, you might see that the connection with one of the apple servers runs uses Multipath TCP.”

  5. pbranham - 10 years ago

    I have been hoping for this feature for a LONG time. I spend about 75% of my waking hours on a college campus, and when going in/out of buildings or just walking past buildings, I have often had to just disable wifi altogether because it would grab a weak signal from inside a nearby building or wait what seemed like forever to drop the weak signal after leaving a building, making it impossible to do basic things like send an iMessage or check email between classes.

    If I’m reading this right, this isn’t actually going to screw up your data plan for those who are already complaining about that. It just keeps an an active TCP for each connection type whenever possible, but only sends data over the “stronger” one? Or just always wi-fi until wi-fi is too weak? Not exactly sure what the nuts and bolts of it say, but the key here is a more seamless handoff, which I have been hoping for forever.

    • Pedro Prego - 10 years ago

      So true. Anyone who was in such campus knows what you are talking about! I have been asking for this since iPhone 4 was released.

    • weakguy - 10 years ago

      That’s exactly what I’m experiencing now!

  6. NQZ (@surgesoda) - 10 years ago

    Microsoft does this with Multi Channel SMB 3.0 — it’s only restricted to SMB 3.0 unfortunately and not ALL tcp/ip applications. This is great news that on iOS it works with all TCP/IP apps.

  7. This is for a very special feature that will be coming in iOS 8. For now, its there to enhance the FaceTime audio feature. iOS 8 changes everything :)

  8. Tom (@Tom) - 10 years ago

    Gosh, some people are thinking this is going to turn into people using cellular data that they don’t mean to. Once you’ve launched an app that connects to the net, you can set if they can access over cellular or not. Go to Settings -> Cellular, then you can either just turn off cellular data (and have to turn it on when you wanna use cellular), or scroll down to the “Use cellular data for” section and disable it for things like YouTube, Netflix, Hulu Plus, etc.

    Personally, I’m on an iPhone 4 and am just on the edge of my coverage from my wifi network (I have to fix this but am not sure why the issue exists yet, may be the fridge between me and the AP, it’s not happening for other equidistant users) and have seen Hulu go “buffering” and resume at low quality, then go back up to high quality. I saw a bit of cellular use (75mb) from that little bit of watching, so I assume I was dropping off wifi and going on cellular regularly. And it was NOT seamless, but I’m on a 4, on 3G, so maybe it’s better with LTE.

  9. THEHD (@TheHenry) - 10 years ago


  10. Michael Rygaard - 10 years ago

    This sounds great ! I have a unlimited plan, and I noticed that after iOS 7 last update, when leaving works WiFi, i did no longer get “sorry Siri is not available, please try later” rather it makes a smooth transfer to cell data. – I would wish Apple stayed out of when i want to use cell data to get data – for instance downloading podcast – as it is now I cant get podcast over 50 mb (or is it now 100 ?) but i can start playing the podcast, so it will buffer the whole podcast, fast like in 10 seconds max over cellular data, then if i stop the app all that buffer is lost and when i resume the podcast it then reload all that data.. so in stead of me using 100 megabyte 1 time i end up using 500 megabytes to listen to that 100 megabyte podcast.

  11. First commercial software to do this? I doubt that. You may want to look at

  12. Yaniv Erel - 10 years ago

    This is not about data charges it’s about reliability, it is not intended for heavy application (yet?)
    Apple is running SIRI with that technology to make it faster and more reliable, if your WIFI is busy it will use 3G and vise versa.

    Pure genius nice Apple.

  13. grandstyl - 10 years ago

    Pls I will like to know the data amount of iOS 7

  14. Aidan Taylor - 10 years ago

    Windows does this.

  15. As Jobs learned from his adopted father, that it’s not about how something looks, necessarily, but how it works.

    The cabinets look great but the screws holding them against the wall deserve just as much attention.

  16. weakguy - 10 years ago

    This sounds amazing! However, I really doubt my iPhone 4S has that and here’s why. Yesterday I was watching YouTube on a weak public wifi. It really took forever to download the vid, so I had to manually turn the wifi off to load the video via cellular network. I also had to refresh the video instead of it continues to load.

  17. my i5 was updated to ios7 , im using wifi and cellular data was off, i opened some of social media applications like facebook, yahoo, skype, but still there is charges, can someone please teach me how to fix this?


  18. Joseph Ayala - 9 years ago

    Well this is coming up here in March of this current year and the proedictions are going on in the market that this operating system going to be a miracle and the users would feel quite pleasent while experiencing it more and more. It has the many more specifications and features that would allow for the first time multipath TCP and the other programs that would go superb.