How to receive SMS message in standby mode in nRF9160?

[Yusuke]

I want to wake up nRF9160 by SMS.

What I want to do:

The nRF9160 usually sleeps to reduce power consumption, and only when it receives SMS it wakes up and send some data by UDP or so.

I succeeded in implementing MQTT(+TLS), but have no experience to implement SMS function.

Any advice?

[Ethan]

Hi Yusuke, sounds like your development would be similar to ours. I am wondering that when you succeeded in implementing MQTT(+TLS) to wake up the device and send some data by UDP, is the LTE module in PSM? Did you successfully implement SMS function? I have been trying to implement the method to wake up the LTE by sending SMS and send some data to the server by UDP. If you don't mind, please exchange the information. Thanks

[Yusuke]

In my case, I'm trying to receive SMS during eDRX. If it received SMS, it's supposed to send data through UDP.

However, I have not been able to do that.

I really want an example program about this. 

[Ethan]

Thanks for your response. 

I see. You are also facing with the same difficulty as ours. Since eDRX and PSM extend the paging period, the LTE becomes dormant and cannot receive any signals during the period. Only thing we can think of now is to trigger the LTE from microchip in the device, which we don't want. 

[Yusuke]

SMS should be received even when eDRX or PSM is activated. SMS is kept at least three days if it doesn't reach a cell phone. You can turn off your cell phone, send SMS from another cell phone, and turn on the former one. You will receive SMS.  

https://www.techwalla.com/articles/can-i-receive-texts-while-my-phone-is-off

[Ethan]

The reference is not what we are doing. In the case, it is not sending trigger on SMS to wake up the LTE module. The article explains that once the LTE module becomes awake, it can receive SMS even though SMS is sent while the LTE module is off. What we want to do is to wake up the LTE module in eDRX or PSM by a trigger on SMS. Isn't it?

[Yusuke]

I think it's not possible to "wake up" dormant LTE modem by SMS. What you can do is to check SMS incoming in the interval which eDRX configures.