iPhone 4S apps work completely fine iOS 4
I have a iPhone 4S that’s on iOS 4, and I was wondering before I turn it on or put anything on it if all the apps work and if you can both call and text.
Earlier iPhone models
A bit too general. It is difficult to answer since apps are so different. An iPhone 4s updated to 9.3.6 will usually work for calls and text (SMS). However, in many countries the mobile phone networks are being updated (or closed), and that may make the iPhone 4s incompatible/obsolete. Most (new) apps are not supported, but a number of already installed apps continue to work.