iMessage from Your Mac or iPad
While iMessage is commonly associated with the iPhone, you can actually access the Apple messaging service on most of the company’s devices. That includes devices that don’t typically have a phone number, such as Macs or iPads.
In these cases, you’ll be able to text other iMessage users, but it’ll rely on the email connected to your Apple ID. Just make sure iMessage is enabled (Settings > Messages on iOS, or Messages > Preferences on macOS.)
If you’re having trouble with some only devices receiving messages, head over to Settings > Messages > Send & Receive and make sure the relevant addresses are selected.