Phone Number Uses


We purchased a phone number for our Hologram SIM, thinking we should be able to use it like other SIMs we have obtained from other carriers/MVNOs, but it doesn’t seem to be working. For what it is worth, we are using the Hologram SIM in a MultiTech MTSMC-LAT3 (or -H5 or -MAT1) socketmodem module, and this is what we are trying to do:

  1. Send a special text message from a cell phone to the cell phone number assigned by Hologram, that we think should cause an unsolicited response (at the socketmodem end):

CMTI: “SM”,xx where xx is an index number of the number of unread messages stored

then when we see this unsolicited response, we read the contents of the message that was sent with:


and then we decide what to do based on the “actual text” of the received message.

  1. Dial the cell number with a cell (or landline) phone, that we think should cause an unsolicited response


every time the line rings at the socketmodem end, which we would use to wake up the remote device.

  1. In addition to sending a text message from a cell phone (as described in 1. above), with other carriers/MVNOs, we are also able to send an email to text using the assigned cellphone number as in:

10-digit for an AT&T SIM
10-digit for a T-Mobile SIM

Does Hologram have a way to send an email to text (ie. should it be sent to “10-digit” or what?).

Currently when we try option 1. above, with the Hologram assigned phone number we received, we never see the unsolicited “CMTI: …” response at the socketmodem end. When we try to dial 1+phone number for option 2. above, we immediately hear a fast busy signal in the calling phone receiver, and never see the “RING” response at the socketmodem end.

What are we doing wrong, or do your phone numbers work this way? If not, why pay the extra $1 to have one assigned?



Hi @BillOtto,

Thanks for your post!

This should work. “Local” phone numbers purchased via the Dashboard will trigger a network operation to deliver a Mobile Terminated (MT) SMS to your device. This should result in the ability to read the message using a command such as AT+CMGL ... or (if you configure it in your modem) the ability to see an Unsolicited Response Code (URC). If this is not working on your device, then that is a strange behavior.

The Hologram global cellular network doesn’t (currently) support circuit-switched voice by default. (Technically, there still is a circuit-switched channel, e.g. used on many Radio Access Technologies or RATs for SMS, but we do not route voice calls by default at present.)

I’m familiar with this capability that you describe. We don’t currently offer this since there would be no way to control who can send to it (a possible security concern for some devices or it could attract unwanted email), but we do currently offer sending SMS to devices via API (and our Dashboard, of course).

Sending via API (or Dashboard) does not require purchasing a phone number, and replies to API-originated (or Dashboard-originated) SMS are sent back to our Date Engine API layer, which can be viewed via API/Dashboard or sent back to your own application via webhook.

The ability to purchase a local phone number is primarily for providing an additional way to send SMS from, e.g., a handset to a device on our network (commonly used for diagnostics or initial configuration of a device over SMS for convenience); however, for customers building more robust products, our API + webhooks offer an integration point between your own application and our platform without the need to purchase a phone number.

As for not seeing the URCs, have you also tried sending (Mobile Originated) SMS using your device? We have an SMS inbox number that you can send to in order to see a message appear in our Dashboard Console. This is the best way to test to see if an SMS is being sent from your device to the network.



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