How To Set Up iMessage With TextNow
Just like for FaceTime, the first step is to create an Apple ID if you haven't already. Click here to create an Apple ID online, or create one on your iOS device by going to Settings > iCloud > Create a new Apple ID.
Next, go to Settings > Messages and turn on iMessage, using the switch at the top of the page. (If the switch is green, it's already on!) Keep the Send As SMS switch off, as seen below:
Next, tap on Send & Receive, which will bring you to one of these pages:
If you are not signed to your Apple ID, you will see the option to Use your Apple ID for iMessage, please select this option.
If you are signed in, choose the email address associated with your Apple ID, or tap on Add Another Email... and enter the email address associated with your Apple ID. If there's a number listed under the "START NEW CONVERSATIONS FROM" section, make sure the number is unchecked and only the email is checked. The number shown is tied to the phone's data plan. Unfortunately, there is no way to use your TextNow # with iMessage at this time. This is due to a limitation with iOS playing nicely with cloud-based phone services like TextNow.
To send an iMessage, open the Messages application on your device.
Like FaceTime, iMessage can only be used between two people with Apple devices. You can't use iMessage to text a person who doesn't have an Apple device.
Only use Messages to communicate with contacts with Apple devices.
Use TextNow to communicate with contacts with or without Apple devices.