Receiving SMS from mobile device

I have a Botletics SIM7000 LTE CAT-M1/NB-IoT + GPS Arduino Shield with a Hologram SIM that has just started behaving strangely in the past 8 hours or so. With the Hologram SIM data plan, I have an associated phone number.

Previously, I was able to send SMS to the shield from my mobile device (iPhone 7) using the associated phone number. Then, all of a sudden (earlier today) this capability stopped working. Now, the only way to successfully send an SMS is using some “obscure” +ddddddddddddddd number. This number is not the SIM number of the IMEI number, but appears to be some number generated by Hologram.

Unfortunately, this creates a chicken and egg problem for me. I can’t send a message to the shield without knowing the appropriate contact number, and I can’t get the contact number without receiving an SMS from the shield. (I can work around this for testing, but the work around won’t work for the average person.)

Did something change on the Hologram side? Or am I just simply trying the wrong way :slight_smile:

My code is pretty straight forward C, with the Botletics enhanced Adafruit FONA library.

Thanks in advance.

- Mark

Any ideas on this one? This is an absolute killer / show-stopper for my project.

- Mark

Is there a better place to ask this question? Three weeks without any response is a bit much.

- Mark

Hey Mark,
Sorry we missed this one.
Is the phone number one that you purchased on our dashboard?

Hi Reuben.

The phone number for the device (from the dashboard ->devices->active->data plan) is in the San Luis Obispo area code. (This was what I was given.) The “number” from which SMS texts are received on my mobile device (iPhone 7) is a 15 digit number, which does not look like any phone number I have ever seen.

As I originally posted, the purchased phone number was originally being used but stopped working about three weeks ago. So I don’t know if it was something on the Hologram end (possible given the sudden appearance of the 15 digit number) or if it was my mobile carrier.

- Mark

I see. I don’t think we’ve changed anything there, but I’ll dig into it and get back here soon.

The real killer for my project is I need to be able, from a mobile device, to send an SMS text to the phone number associated with the Hologram SIM. In turn, the device using the Hologram SIM can then respond to the number of the mobile device from which the SMS text was received.

This is where having the 15 digit number breaks things. As far as I can tell, this number doesn’t show up on any of the Hologram dashboard pages.

- Mark

Ok yeah, so our SIM cards are usually programmed with a special non-geographic phone number starting with +8823. This is probably the number you’re seeing send the SMS. When you use circuit-switched SMS to send from the device, this is always what you will see as the sending number even if you purchase a phone number.

The way around this is to use our SMS-over-ip system to send the SMS instead of replying directly via circuit-switched SMS. Those messages get routed through our cloud and if you have a purchased phone number it will show as coming from that number.
Another plus of this message is that you avoid the 19 cent SMS fee and pay for only a small amount of data usage instead.

You can also send a circuit-switched message to +447937405250 and that will end up in your cloud messages and you can make a route that passes it along somewhere via SMS.

Note that the system has always worked this way so not sure how you were seeing the other phone number before. Perhaps you were routing messages through our cloud at some point?

Here’s some docs on all this:
https://hologram.io/docs/guide/connect/protocols/#circuit-switched-sms
https://hologram.io/docs/reference/cloud/embedded/#send-an-sms-via-the-hologram-cloud
https://hologram.io/docs/guide/cloud/data-router/#sms

Hi Reuben.

Ok yeah, so our SIM cards are usually programmed with a special non-geographic phone number starting with +8823.

OK. This is exactly what I’m seeing.

Perhaps you were routing messages through our cloud at some point?

Or I was just confused… always a possibility. :slight_smile:

Since there doesn’t seem to be anywhere to (easily) obtain the +8823xxx number, this leads to the question: is it possible to contact the device (with the Hologram SIM) from another mobile device without requiring the device to send an SMS text to the mobile device first?

Unless I missed something, which is always possible. :stuck_out_tongue:

- Mark

Oh, so that number is visible via our API on the /links/cellular call for that SIM if you want. It’s the MSISDN number.
That being said, most carriers can’t route SMS to the non-geographic number so you would really only be using it for identifying where messages are coming from and not actually to send a message.
This is why we sell the separate phone numbers so for the folks out there that need to send an SMS from a mobile device to one of our SIMs they have an option.
Can chat around here to see if we have any ideas for doing what you want. I think we usually recommend just doing SMS-over-IP

OK. I just ran a simple test. Here’s what happened, and let me know if it is what you would expect to see.

I sent an SMS text from my iPhone (which is also on my WiFi network here) to the MSISDN number and received the expected response from the MSISDN number. I then sent an SMS text message to the purchased phone number. I got a response from the MSISDN number.

So it looks like I can send an SMS text to either the MSISDN number (using my carrier) or the purchased phone number, but the response is always “from” the MSISDN number. Or more simply, always send to using the purchased phone number, but responses will always be from the MSISDN number. Does this sound correct?

- Mark

Yes, that sounds correct, but I wouldn’t rely on being able to send an SMS to that number as many phone carriers won’t deliver it.

OK. So it sounds like the simple to via phone number from via MSISDN number is the correct view.

One of my constraints for my project is to have device to device communications using only SMS. So cloud, TCP/sockets, etc. really can’t be used.

- Mark

Reuben, thank you very much for your help.

- Mark

You’re welcome. And yeah, if that number is working for you then go ahead and use it, but I wouldn’t build a mass market product around that

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