Can I USE a ATT prepaid sim card in the Avnet M14A2A Cellular Shield

DelphiDBW's picture

I was wondering if I could purchase a prepaid sim card and use it with the IOT Cellular Starter kit to send SMS messages to and from using the cell number?  The kit comes with a sim card that works with the IOT but I want to be able to send SMS messages directly to the shield.

Also Does the Avnet M14A2A Cellular Shield only work with ATT sim cards or could I use a TMobile Sim?


LightCollector's picture

Hi, Sorry I do not believe that is possible.  The M14A2A is considered an AT&T IoT/M2M device and uses a different APN ( than the cellular phones do (often: broadband).  The sim card that comes with the kit is the only way I know to use the shield and has it's own pre-paid data plans.


Even with the kit SIM you cannot send an SMS to a regular phone number, this is not the M14A2A's issue it is the way the ATT M2M cellular network is on purpose setup.  You can send an SMS between devices using the MSISDN number, see the WncControllerLibrary on team Avnet's mbed developer site for a C++ class that gets the MSISDN number and can also send SMSs.  The other place SMSs can be sent is from the 14A2A to AT&T control center.  When you register your kit SIM card you are also setting up a control center account.  You can send messages from control center to shield as well, again using the MSISDN number that is derived from the ICCID number of the SIM.


If you want to send an SMS from the shield to a real phone, you have to use a service like Twillio or Kandy, which you talk to via a standard internet protocol and then those services bridge the divide over to the cellular APN.  You can also use AT&T's FLOW servers to take input from the M14A2A and in FLOW they have a Twilio node.


Best Regards

Teeny's picture