Why does some iphone users get angry when they get green bubbles
The green bubble could signify that a) You don’t have internet connectivity b) your recipient doesn’t have internet connectivity or c) your recipient is on a device other than an Apple device.
iMessage is an MMS (Multimedia Messaging Service) client used by Apple and uses Apple’s servers. Messages are sent over the internet. If the servers are not reachable, the message is sent by SMS using the carriers standard SMS (text message) infrastructure instead. Green bubble = SMS, Blue Bubble = MMS within iMessage.
If the sender can’t reach the Apple MMS servers, it’s usually because their data connectivity is spotty or non-existent. That can be annoying. their message would go out as an SMS text via the carrier, instead.
Similarly, if the recipient doesn’t have connectivity to those servers, it means they would appear ‘offline’. Your message will be sent via the same SMS method if it’s not of a multimedia type. If it is, the send will fail.
If the recipient doesn’t have a registered Apple ID with an Apple device, the Apple servers wouldn’t know who you’re trying to reach; so if goes out as SMS.
The difference is that MMS allows for Multi-media content; such as pictures or videos. SMS is “Short Messaging Service” and is limited in content (no multimedia).
Also, iMessage MMS has a receive receipt feature. You get confirmation that the message was delivered.
It can be very annoying if you’re trying to share something more than a text message.