Newer devices will generally not have any trouble when conducting video calls. Even so, there are some older devices that do not support video calling or only provide a limited experience.
When using an Android device, you will need at least the JellyBean version (version no. 4.1). There is also one specific Samsung Android version of 5.1.1 (Lollipop MR1) on which video calling does not work. For general reference: at the time of writing, the newest version of Android is no. 8.1 (Oreo).
BlackBerry devices (BB10) and Ascom Mycos cannot be used to conduct video calls.
When it comes to iOS, you can use any device that can run the messenger to start / participate in a video call. However, the older your device, the more trouble it will have running a smooth video call.
Generally speaking, these iOS devices can be used to conduct video calls (using iOS version 10.0 on 64-bit devices):
- iPhone 5s (and newer)
- iPad 4th generation (and newer)
- iPad mini 2 (and newer)
- iPad Air (and newer)
- iPad Pro (and newer)
- iPod touch 6th generation (and newer)