Ting Mobile has been a popular MVNO operator for many years. Like Google Fi, it is aimed at people who do not use much cell data, with the ability to mix and combine levels for minutes, texts, and data usage. A great strength for Things has been the ability to use either a GSM or CDMA network, but it will soon go away.
Things now allow customers to use either GSM or CDMA SIM cards, even across different lines on the same account. GSM cards use T-Mobile's network, while CDMA cards use Sprint. However, things have announced that it is ending its partnership with T-Mobile, and all existing GSM SIM cards will cease to function by December 1
It is not immediately clear what device compatibility will look like when the transition is complete, but the move will definitely cut out a large number of phones from working with Things. Verizon has a whitelisted network that only certified phones can connect to, but even though it does not apply to MVNOs, many GSM devices (such as imported Xiaomi phones) lack support for most Verizon LTE tapes. Some Ting customers also use T-Mobile locked phones, which definitely doesn't work after transition.
Things have already removed all GSM phones from their online store, and the company says Verizon support should go live before the end of 2019.