For those of us who rely on the cellular networks to get online - one longstanding annoyance has been that it is often impossible to move devices from one carrier to another.
Often the reasons are technical (incompatible technology and frequency bands), but very often devices are sold "locked" to the original carrier, and without unlocking them first they are tied to that carrier forever. And up until now - unlocking your phone or hotspot without the carriers permission was technically illegal.
Congress has at last passed a law (soon to be signed) that makes unlocking legal, and along the way carriers have already put in place programs where they will unlock devices for customers out of contract in good standing who make a request.
It is really handy to have a single device that supports multiple carriers, especially for us traveling types.
When your contracts are up - get your devices unlocked. It increases their resale value, and their future utility. You may have to jump through some annoying hoops, but it is worth it.