Once installed in a device and activated for a particular service plan, is there any difference between T-Mobile pre-paid and post-paid SIM cards, or are the cards themselves exactly the same? What I want to do is order a SIM card for future use, without ordering a service plan. Later I want to activate the SIM card for post-paid service. T-Mobile's website won't allow you to order a SIM card from the post-paid part of the site without also ordering a service plan. So I want to know if it will be effective to order a pre-paid SIM card and later activate it for post-paid service.
Will there be any difference in service or functionality of a phone on post-paid service based on whether a post-paid or pre-paid SIM is installed? Do both equally support all features, such as LTE? My understanding is that T-Mobile prioritizes data traffic of post-paid customers higher than pre-paid -- how is that implemented, does it have anything to do with the SIM?