Same here. I'mlooking for an answer to this question myself.
I apologize for the delay in getting back to you on this. Did you still need assistance?
In general, the watch may not need a different SIM. If it's a watch with an embedded SIM, we update those with a virtual SIM on our end since you cannot remove it from the watch.
As for using it on another phone, generally another SIM is sent. Did you sign in through the app and use it that way since you stated you are using it on two phones? If not, we may need to get some more information from you to ensure it's all set up correctly for you.
thank you. im up and running good for now. things got a bit confusing in the beginning. but everything seems to be runnning well as of this weekend.