The arrival of the LTE/4G wireless standard in the United States, and its adoption by the country's two largest super-carriers AT&T and Verizon was supposed to open the door for true equipment interoperability, allowing customers to take devices purchased from one carrier to another. In the past, incompatible network standards (GSM - AT&T and CDMA - Verizon Wireless) made device portability a practical impossibility. The arrival of LTE could have changed everything, with device manufacturers using chipsets that would allow an iPad owner to switch from Verizon to AT&T without having to purchase a brand new tablet.
Example: Imagine buying a television set from an NBC station and finding out the only TV station the set will receive is NBC. Limitation comes not from technology but [from] wireless carriers and equipment maker's specifications.