Group chat confusion

[little_ames]

My sister just sent a group chat to me and my mom. My mom and sister both have iPhones. The message was a picture and I downloaded and then I replied. Well, my mom text me back with "???" because she didn't even get the group chat. My reply just sent to my mom.
So what in the world happened? I'm assuming this is because of imessage? Do I need to tell my sister for future reference that she needs to send me things individually?

 

[Gekko]

My sister just sent a group chat to me and my mom. My mom and sister both have iPhones. The message was a picture and I downloaded and then I replied. Well, my mom text me back with "???" because she didn't even get the group chat. My reply just sent to my mom.
So what in the world happened? I'm assuming this is because of imessage? Do I need to tell my sister for future reference that she needs to send me things individually?

3 parts -

1. make sure that you have turned off iMessage on your old iPhone.
2. delete your old phone number and delete/unregister all old iPhone(s) from your Apple ID web profile at supportprofile.apple.c0m.
3. make sure iPhone-using friends App Settings are set correctly. By default, sending as SMS is not selected in IOS 7. To enable this go into settings>messages>send as SMS. This will send messages as regular SMS messages when imessage isn't available.

Issues with texts after moving to Android from iPhone? Here's an easy fix! | Android Central

 

[little_ames]

I've never had an iPhone, so that isn't the problem.
I can text individual iphone users no problem. This was a group chat between me(m8 user) and two iphone users.