So if you are on a cellular plan for the S3 and selling the watch and moving to the S4, do you remove the data plan from the S3 when unpairing or keep it so that it restores to the new watch.
Apple support says to remove the plan so I guess that means that your carrier will need to assign your plan to the new watch
“Tap Unpair Apple Watch. For Apple Watch Series 3 (GPS + Cellular), tap Remove [Carrier] Plan. If you aren't going to pair with a different Apple Watch or iPhone, you might need to contact your carrier to cancel your cellular subscription.”
Apple support says to remove the plan so I guess that means that your carrier will need to assign your plan to the new watch
“Tap Unpair Apple Watch. For Apple Watch Series 3 (GPS + Cellular), tap Remove [Carrier] Plan. If you aren't going to pair with a different Apple Watch or iPhone, you might need to contact your carrier to cancel your cellular subscription.”