Question: I am on a slow Internet connection that comes with a monthly FUP (Fair Usage Policy) of 30 GB, and in our home we use this for browsing the Internet or downloading what’s important. Right now, my problem is that I don’t want to install or update my iOS devices via WiFi as doing that will cost us bandwidth.
We don’t want to waste our Internet bandwidth, and at the same time we would like to update multiple iPhones and iPads. What is the best way to do it?
Answer: Downloading the latest iOS update on your iPhone or iPad via WiFi is just one way. We have so many. And the WiFi method is good if you have only one device.
But as you have more devices, what you will need to do is manually install iOS 8 using your computer.
This can be achieved by downloading the iOS’s core file, which is the IPSW file. So, for example, if the latest iOS firmware is named iOS 8.4.1, then you have to download the IPSW file of iOS 8.4.1.
Once that is done, you have to manually install this downloaded file on your iPhone / iPad. This can be done when you plug your iPhone / iPad into your computer and launch the iTunes player.
For more details, follow this guide: How to Install IPSW Files
Note: Say that you have only one iPhone 6, one iPhone 5, and one iPad. In that case, you have to download a different IPSW file and manually install it via iTunes. This will not save your bandwidth.
But if you have the same iPhone / iPad models with you, and you plan to update to the latest firmware (one specific firmware), then upgrading manually makes a lot of sense as you are going to download one IPSW file (one for iPad and one for iPhone).