Messages – on iOS/iPadOS the messaging goes by a proprietary protocol called iMessage. If the recipient down’t have an Apple device, this defaults to SMS Text messaging.
FaceTime / Zoom – The former is Apple, the latter is what we’ve used over the pandemic. Both nice apps.
Signal – my preferred alternative to WhatsApp. Secure, encrypted end-to-end communication. Open Source. I subscribe to the service to help their running costs. If you haven’t installed it yet, please do and join our Computer Group. I wondered about Telegram but I feel that it’s just a bit close to Russia to trust.
twitter – I guess that my use of twitter will even further decline, as has my use of Facebook/Instagram/WhatsApp. I have obtained a Mastodon account but have not really experimented much with it as yet. It’s another Open Source project.