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Sending SMS messages from data card?

ziesemer-sec
Member

We were interested in using a setup with a MiFi 4G LTE data card (USB620L) as an on-premises SMS gateway, for use of sending “pager” notifications of system-down events, etc., within our network - even if our primary Internet connections became unavailable.  This “works” in that I am able to successfully send an SMS to myself on another number from the card, but in the process of doing so it hangs the card until it eventually returns an error.  So something clearly isn’t quite correct here, and I’m hoping there is just an additional configuration or such that needs to be applied either locally or in the card’s configuration on the VZW network to remedy this.

I seem to recall that prior VZW data cards I had used had an option directly in the UI for sending and receiving SMS messages.  The current web-based UI is receive-only.  It is documented as such in the manual, and seems to be intended for “system notifications” – but I was also able to send a SMS from another phone to the card’s # which appeared in the list immediately.  I don’t see any additional options in the available Dashboard Application, nor could I find a way to get an AT modem interface to the data card from Windows.

I did also find Verizon’s “Linux Integration Guide” for this card at http://www.verizonwireless.com/dam/support/pdf/user_guide/u620-linux-integration-guide-7-17-15.pdf - which was one of the primary reasons we chose this card and solution through VZW, as this connectivity was intended for a Linux device.  This guide was written against a 3.16 Linux kernel that required patching of the kernel for “Enterprise Mode”.  Fortunately, we’re using an updated 4.4.13 Linux kernel that already has the necessary modifications included for the USB620L.  Here are some details that I’m currently able to interrogate from the card over the provided AT interface (some outputs partially masked here with ********):

AT

OK

ATI

Manufacturer: Novatel Wireless Incorporated

Model: USB620L

Revision: 2.44.3  SVN 0 [2015-05-13 13:56:54] (Release Build - nvtl)

SVN: 00

IMEI: 9900063********

+GCAP: +CLTE2, +CGPRS, +CIS707-A, CIS-856-A, +MS, +ES, +DS

OK

AT+CGMI

Novatel Wireless Incorporated

AT+CGSN

9900063********

AT+CIMI

3114802********

OK

AT+CSQ

+CSQ: 13,99

OK

AT+CBC

+CBC: 2,100

OK

So full AT connectivity to the card appears to be working as-expected, and all of the above commands complete instantly.  I can also prepare to send a text-mode SMS message, which also returns instantly:

AT+CMGF=1

OK

However, once I send a test message (920-###-#### is an iPhone on the same parent Verizon account):

AT+CMGS="920#######"

> Testing 123

(followed by Ctrl+Z for “end-of-input” to send) – the message is received almost immediately by the iPhone, but the AT serial console to the data card then hangs for ~3 minutes before finally returning:

+CMS ERROR: 500

Do we need to validate that the configured SMS center number here is correct?  (I did not enter this, it was configured by default.)

AT+CSCA?

+CSCA: "+19037029920",145

I can repeat the same with a command-line tool provided specifically for working with SMS (vs. hacking the manual “AT” commands):

$ time gammu sendsms TEXT 920####### -text "Testing 123"

If you want break, press Ctrl+C...

Sending SMS 1/1....waiting for network answer..error 500, message reference=-1

Unknown error.

real    3m4.968s

user    0m0.080s

sys     0m0.240s

Again – despite the hang and the error, the message is successfully sent and received.  However, this would hardly be acceptable for any real use as-is – if for no other reason in that we’d have no visibility into which messages were successfully sent or not.

I hope I have adequately demonstrated that there are no concerns here with the choice of client or its configuration.  It is communicating with the modem successfully, but the modem is not responding as-expected.  I believe there to be an issue either in the modem’s firmware that could be updated for, or potentially a configuration at VZW for this line that needs review.

If there is an alternative data card that we should consider for these purposes (given the above), please advise of that as well.

Thanks!

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Re: Sending SMS messages from data card?

ziesemer-sec
Member
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Re: Sending SMS messages from data card?

Weth
Sr. Leader

Doesn't

I got final word back from our device team that we do not support SMS through AT commands.

Sound definitive?

we use SMTP solution to send text via email. 

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Re: Sending SMS messages from data card?

ziesemer-sec
Member

Sorry, it doesn't.  If I had a dollar for every time I was told that something wasn't supported, but that the question actually just wasn't raised to the proper team or resource to receive proper attention, I'd be very rich.

As previously noted, what makes this significant for me is that the functionality "works" in that a sent message is received almost immediately by the destination device.  As such, the functionality exists - but apparently has a bug that otherwise makes it unusable in real practice.  (Having the command hang for ~3 minutes and then eventually return the "CMS ERROR: 500" will cause issues with gammu or other integrations.)

Without having a proper technical resource from Verizon and/or Novatel look at what is actually happening here, it is impossible to know if this would be a trivial firmware fix or something in the device's configuration profile @ Verizon - or if there are more significant issues at play that, if explained, would provide for a reasonable explanation as to why this isn't working as expected and can't be supported.

SMTP is probably my backup plan here - but native SMS would have a number of significant advantages to SMTP, including not needing to have a functional IP stack / address on the device to communicate.

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