QnA - Cellular IoT Fundamentals

Feel free to share any questions related to LTE-M, NB-IoT and LTE Cat1 in this thread.

One of our legacy providers (AT&T) requires an APN. We have this set in our device FW, so, not super simple to change. The Monogoto SIM seems to work fine though - and you obviously have a different APN. I’m assuming our modem is reporting the AT&T APN to your system, which is promptly ignored. Does the APN have any relevance here? Are there risks of leaving our system the way it is?

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Hi @ChrisP,

Monogoto supports AT&T’s network, so when using AT&Ts APN your device still works. However, you are not able to use any other network other than AT&T. Only when using Monogoto’s APN: data.mono you can access all ~500 networks.

To test if your device is connected successfully, you can look at the Monogoto Hub and look at the time and date when the device is last seen.
Screen Shot 2022-04-29 at 15.29.51

We need to tweak our firmware so that when it detects a Monogoto SIM (by ICCID), it changes the APN accordingly. Example, Verizon SIMs always start with 89148 for us. Are Monogoto always 89999? Do we need to look as far as 8999911240? Thanks -

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Hey Chris,
At the moment, Monogoto’s SIMs ICCID begins with 8999911, and that is as far as you should go when analyzing the ICCID to detect the provider to match the needed APN.

Please note that other beginnings of ICCID might be added in the future so maybe you should consider to have check the instated SIM ICCID with an array of those beginnings, although I would added that in phase 2 of the tweak :slight_smile :slight_smile:

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I assume that you are using the AT+ICCID (else please tell me).
Would it help you if we store the required APN on the SIM card so that it can be retrieved via an AT command?


#CCID: 89999112400xxxxxxxxx


Frank, as for storing the APN on the SIM, I think that would only help if the Monogoto APN changes. Otherwise we can just hardcode it, as we would for AT&T.


well, the APN value provided by the modem has relevance - else it wouldn’t be there. The matter is unfortunately not a trivial one and depends on several factors (lots of ‘if’ and ‘but’). You are on the lucky side if it works out like you experienced.
However, we recommend that you set our default APN on the modem with the +CGDCONT command as Laurens stated. Having said that, please do get in touch with our customer support if you don’t find yourself on the lucky side.

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