When iOS 8.1 was launched, Apple added a new feature called Text Forwarding, which enables SMS text messages to be sent and received on the iPad. If someone sends you an SMS text message, it is received on your iPhone first, before being forwarded to the iPad. In the same way, when you send an SMS text message from your iPad, it is sent to your iPhone and then it is forwarded from it. In order to be able to use Text Message Forwarding, your iPhone and your iPad have to use the same Apple ID for iMessage and they need to be connected to the same WiFi network.
What happens if you don’t see the Activation code?
During the setup process for Text Message Forwarding, an activation code should appear on your iPad. Then you need to enter the code on the iPhone so that Text Message Forwarding is authorized to the iPad. If there is no activation code on the iPad during the setup process, you will need to make sure that the iPhone and iPad are connected to the same wireless network. In addition, you need to go to the two devices and check that the same Apple ID is being used for iMessage. You can go to Settings, then Messages and Send & Receive to verify this. You should see the Apple ID at the top of the window.
If the “Use Your Apple ID for iMessage” option is displayed, it means that you are not signed in to iMessage with your Apple ID. Tap the button and follow the on-screen instructions to sign in to iMessage. In order to use the Text Message Forwarding feature, you have to be signed in to iMessage on your iPhone. The Text Message Forwarding menu may not be shown on your iPhone if you are not signed in to iMessage.
If you still don’t see the activation code on the iPad, the next option would be to reset iMessage on the iPad. You can do this by going to Settings, then Messages, Send & receive and uncheck the email addresses in the section called “You Can Be reached by iMessage at”. Tap your Apple ID at the top of the screen and then select Sign Out.
Once you have signed out, check that the slider for iMessage is set to the off position. Then press and hold the Sleep/Wake button and the Home button at the same time for at least 10 seconds to reset the iPad. The screen should go blank while you are holding down the buttons. Keep holding the buttons until you see the Apple logo on the screen and then release the buttons.
When the iPad restarts, allow 5 to 10 minutes and then turn the slider back on. After that, sign in with your Apple ID. The iMessage activation should continue as normal and once iMessage is activated, you can again to Settings, then Messages, Send & Receive and ensure that any email addresses that you want to use for iMessage are selected. Text Message Forwarding can be set up once you have completed the process to reset iMessage. If there is still no activation code, even after iMessage has been reset, you can try resetting iMessage on your iPhone to see if that works.