Why can’t I send a text from iPhone to Android?

Make sure that you’re connected to a cellular data or Wi-Fi network. Go to Settings > Messages and make sure that iMessage, Send as SMS, or MMS Messaging is turned on (whichever method you’re trying to use). Learn about the different types of messages you can send.

Why can’t I send messages from my iPad to Android?

If your old iPad was sending messages to Android devices, you must have set up your iPhone to relay those messages. You need to go back and change it to relay to your new iPad instead. On your iPhone, visit Settings > Messages ? Text Message Forwarding and make sure that relaying to your new iPad is enabled.