What if we took DIGITS to the next step? Getting rid of "phone lines".
The fact is: Voice and Text are already unlimited on all REAL phone plans. The main difference now is how they charge for data.
So happens if we get rid of "phone lines"?
Every "voice line" becomes a data line and you can use the "phone number" on any device whether it's a tablet, computer, phone, or whatever. Then you zero rate the data from DIGITS used to make calls and texts, like Music Freedom or BingeOn, for the people not on unlimited data plans. Now you wouldn't use data when making a "phone call" or text from any another T-mobile device you have. Right now it all counts against the second devices data.
Plus all of your call logs and texts could be immediately synced across all of your devices. As it is now the device with the SIM card assigned won't log texts the same way as the other devices. Any text sent or received shows up on any of the DIGITS devices, but the parent device wont be able to see texts sent out from other DIGITS devices. If the first device didn't have to worry about the conflict of receiving calls and SMS from the network as well then you could make it just like all your other DIGITS devices.
Do this and every un-metered device (doesn't use a data bucket, ie: another carrier's data) becomes equal. All you have to do is pick up the device and log into DIGITS. There would be no difference between first phone, second tablet, or PC. No difference between LTE, Wi-Fi, or Ethernet.
Another plus is probably less taxes from regulations on the "data lines" as opposed to "phone lines".
Now you can sell data and phone numbers completely separately and only pay for exactly what you need.