Try going to SettingsCellular.Cellular Data (make sure turned on to green). I had the same problem. I just turned off MMS option from Settings >> Messages >> MMS and now I can send group messages.
Many android devices use Google Messages, the free group text app that comes installed by default.
Apple Only Fully Supports Group iMessage Chats Yes, that's right! While it's possible to use any type of group chat, your iPhone only truly supports iMessage-only group conversations. This is where all participants use Apple devices and the messages appear in blue bubbles.
To send a group MMS message on an iPhone, make sure MMS Messaging is turned on. Go to Settings > Messages and turn on MMS Messaging. If you don't see an option to turn on MMS Messaging or Group Messaging, contact your carrier to see if your plan supports Group MMS Messaging.
Launch the Messages app on your Apple device. Tap on the Compose Message button. It's located in the top-right corner. Now you can either type in the name or the phone number of the first person you want to join the chat or tap on the add (+) symbol and look for them in your contacts list.
Sometimes, sending a group text won't work unless you enable the group MMS option in the Messages app. To do this, open the Messages app and tap on the three vertical dots in the top-right corner, and select Settings. Then, go to Advanced and enable MMS under Group messaging.
You can also send a DM from a group:
Check your group conversations settings However, if you're having trouble sending or receiving group messages, make sure this setting has not been accidentally turned off. Navigate to and open the Samsung Messages app. From the Conversations tab, tap More options (the three vertical dots).
If it still doesn't work, reasons why include: The person you're trying to message deactivated or deleted their account. You've blocked the person you're trying to message or they've blocked you. You're trying to respond to a group conversation that the other members of the conversation have already left.
Your iPhone sends group messages as individual messages to non-iOS users. The reply comes back as an individual message as well. You may also get individual replies to group messages if users disabled iMessage or Group Messaging on their devices.
Navigate to your group's main page. Click members from the navigation menu on the top right, above the group search bar. Scroll down to the bottom of the page and click broadcast a message to all members. Enter the subject and body of your message, and then click on send.