Calling with your business number on your mobile
That's not yet possible through a mobile app — eSIM, which would make this work, is still "coming soon".
Telsmart doesn't currently have a separate mobile app. You can already call and be called through the desktop app for Mac or Windows, directly from your dashboard under Get the desktop app.

Good to know: once eSIM is available, you'll link it to an existing Telsmart number — see How do I activate my eSIM?