1. WiFi harmony- Ensure that your Mac and iPhone are connected to the same WiFi network.
2. iCloud account harmony- Ensure that your iPhone and Mac are connected to the same iCloud account. This should only apply if you have multiple iCloud accounts.
3. Up to date- Ensure you have the latest version of iOS on your iPhone. Go to Settings>General>Software Update to see if you have any updates.
4. Setup- Go to Settings on your iPhone and go to Messages>Text Message Forwarding. Your other available devices will be listed. Switch the setting for your Mac to On.
5. Verification- Once you turn your Mac to the On position from your iPhone, you will receive a verification code notification that will be sent to your Mac. Locate the verification code on your Mac and enter it into your iPhone. This code will be of a numerical type and will be six digits in length. Once the verification code has been confirmed, you will now be able to send and receive SMS text messages on your Mac as well as your iPhone.