Today I was using my IphoneX and received a call. The phone lost connection with smartlink and when I tried to reconnect I got a server error. I was not able to reconnect for over 8 hours untilI got home. Now everything is working fine again
If you are where WiFi is good, you can set the phone for WiFi calling and then will allow you to do both at the same time with a Sprint phone. I do it all the time. Providing the same capability on the cell signal in Sprint's roadmap but they don't have a timeframe for it yet.
Some good news after researching both CDMA and GSM then the new 4GLTE with Verizon I discovered that Verizon has been moving to GSM under 4GLTE and will be included under 5G. I also found that you must activate the voice and date mode on your phone that is now available on iPhones that have the latest updates. It’s very easy . Go to setting then to cellular. Be sure cellular data is turned on . Then go to Cellular data options enable LTE to voice and data then go to roaming and be sure both voice and data are Roaming. I can now use smartlink and take a call.