T-Mobile subscribers who have iPhones may now use an eSIM even when they’re on a postpaid plan.
eSIM provide several benefits, one of which is having both work and home phone numbers in one iPhone. A separate SIM will prove to be useful when you need one specifically for data or calling purposes while traveling overseas.
The transition from physical to eSIM on a new iPhone will require you to call support services so they can do the switch. Also, while both numbers may be used for text and calls, only one can be assigned to provide cellular data services.
Only newer iPhones, e.g., iPhone XR, iPhone XS Max and iPhone XS can support the eSIM format, but Apple plans to add it to future iPhones. Activating prepaid eSIMs may be done via the T-Mobile app, while postpaid eSIMs will require a visit to a T-Mobile store.