Make sure that both devices are connected to the same Wi-Fi network and that you’re signed into FaceTime and iCloud on both your Mac and your iPhone using the same Apple ID. Make sure your Mac is toggled on to receive text messages.
Sometimes a simple solution like this works wonders. In case the iMessages don’t work with the above steps, restart your iPhone or iPad. You can even use FaceTime without having a phone number or SIM. You can send text messages, documents, videos, links, photos, etc. With the exception of regular SMS, all other functions of iMessage work just fine. What works in iMessage without a phone number or SIM? Select the email or phone number you want to use for iMessage. To fix that, go to Settings> Messages> Send and Receive. But sometimes that doesn’t happen and users won’t be able to send or receive iMessages if they are using a different SIM card or no SIM card. If there isn’t a SIM card on the device, Apple usually automatically moves the profile to an email ID. Basically, you will be identified in iMessage via your Apple ID if you use it without a phone number. And of course a working internet connection is also required. Since iMessage also works with an Apple ID, you’ll need to select the same in the Messages app’s settings to use iMessage without a SIM or phone number.
How to use iMessage without a SIM and phone number If the internet is not working, iMessages will not be sent or received. This can be done via mobile data (if a SIM card is installed) or Wi-Fi.
It only works if you have a working internet connection. The iMessage service can be used with a phone number, Apple ID, or both. You can use it without a phone number or SIM card installed on your current device. However, if your phone number is not working or there is no SIM card in your device, you will not be able to send or receive SMS. You can also send SMS to non-Apple users. However, the SMS service does require a working phone number and SIM card in order to function. The iMessage service is present in the regular messaging app.