Yes I have sprint. I went from a S3 with cellular to an S4 with cellular. I am trying to not be confusing as LTE is a speed which can be used for calls but is usually thought as being used for data. I am not at all surprised you could get no information from sprint chat. When I got my S3 setting up for cellular I got luck and found a tech at a sprint store that knew how to set it up.
I anticipated fun time setting my S4 up with my Sprint watch cellular number. I was pleasantly surprised when I began the S4 pairing with my Xr Max a screen appeared on my iPhone that asked if I wanted to transfer my cellular watch number from the S3 to the S4 - or something like that. I said yes and it worked! When I checked my sprint account online it showed the new watch as belonging to the cell number for my phone.
Now I use the S3 for swimming - my form of exercise - and the S4 for everything else. The S3 will still get a call if the phone is close by and I am wearing it. Which ever watch I am wearing works with the phone just fine but the only one with its own cell number is the S4.
Lisa