Just to be clear, you cannot use a Verizon SIM on the MC7700 Sierra Module, since this module is GSM/LTE carriers like AT&T. Similarly, you cannot use an AT&T SIM on the MC7750 (Verizon only)
Just FYI - For M2M applications, both AT&T and Verizon plans have significant downside - neither allows for modem terminated traffic, at least not very easily. That means that, if you want to send a message to a remote device, you will have to use SMS, or buy and expensive static IP SIM from Verizon.
Agree with Curtis, first, local ISP must offer LTE network. Then you can get a SIM card from them to start your development.
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