Please try each of the following steps that you haven't already tried.
Step 1
On the Mac, open the iCloud preference pane and sign in if you haven't already done so. Check the box marked Contacts. Do the equivalent on your mobile device(s).
Aug 20, 2019 How to Text from a PC with an Android Phone. If you have an Android phone and a Windows PC, you can text from your PC with the Your Phone app built into Windows 10. That’s one of the big draws of Apple’s Messages app—if you have an iPhone, you can text with your Mac. Well, if you have an Android phone, you can text from your Windows 10 PC.
- Apr 25, 2020 How do you add a Phone Number to iMessage on Mac. This method will help you to add phone number to message from your Mac. Open Message Application and click on “Messages” on the menu bar; Click on Preferences Accounts; If you are not logged, login with your Apple ID and password by click on sign in; Click on Add email and your phone number.
- Are you looking for an ideal phone messaging system to keep your personal and business contacts separate? Here’s some good news for you. With 2nd phone number app App experience an ideal phone messaging and calling system for your business. Choose a number.
Make sure that your contact accounts are enabled in the Accounts tab of the Contacts preferences window.
Step 2
From the menu bar, select
▹ System Preferences... ▹ Language & Region
Numbers Mac App Store
From the Region menu in the window, select one of the preset regions. If one is already selected, choose a different one, then change it back. Close the preference pane. Quit and relaunch Messages.
Mac Messages Phone Number
If you still have the problem after taking those steps, post your results.