SparkFun LTE CAT M1/NB-IoT Shield - SARA-R4, SMS sent but not received

Wireless & IoT Cellular
1

Hello,

I am having issues with the SparkFun LTE CAT M1/NB-IoT Shield - SARA-R4 (with Hologram SIM Card) and the use of the LTE Antenna 100mm FPC u.FL - VT4GFIA-6.

I have been using the Arduino UNO with the Shield, and followed the Hookup Guide to register the operator, which was successfully able to connect to AT&T, and shows connection on the hologram account. Following connection I tried the 01_Send_SMS, I changed the phone number to my own with the 1 for US.

The code uploads successfully and shows “Sending: “Test” to 1720*******”. But my phone never receives the message.

We thought that adding the external antenna would solve the issue, and it was connected, the jumper was cut and re-soldered to the external. However, I still have the same issue where no message is received.

I do not believe it is an issue with the hologram SIM card as I was able to use Examples 02_TCP_Send_Hologram and 03_TCP_Recieve_Hologram. I am also being charged on the SIM card for SMS messages that are “sent” but not received.

I have tried the troubleshooting tips on both the Hologram and Sparkfun pages and am still not receiving any texts. My phone’s carrier is Verizon and I was wondering if that was an issue.

Thanks

2

Hi, I have not used this particular shield. But I have worked with other GSM modules and shields like SIM900, SIM 808, etc. when working with GSM modules I have noticed one thing. These GSM modules often fail to perform without a sufficient power supply. For instance, when I worked with the SIM808 shield, I always had to power my whole setup with the supplied 9V adapter. Powering up the Arduino from USB didn’t work. What power supply are you using for your shield? Is it being registered to the network? Can you see the Blue led glowing? Kindly check.

And if you ever consider something simpler, you can try SIM900 according to this tutorial: https://www.theengineeringprojects.com/ … mands.html

SIM900 is quite easy to use.

3

I found that adding the + before the 1 in the number. IE “+1xxxyyyyyyy” made all the difference. Without the + nothing went through. Add the + and ‘Bob’s your Uncle’ and messages go through.