Sending Blank SMS Messages


Hey Guys,

I’m having an interesting issue where i’m sending blank SMS Message (either through at commands or via OpenAT App).

Is there something that I need to do prior to sending? It’s not the sim card that i’m using as I’ve chucked that into my personal cell phone & it works as expected.

The previous sim that I had worked, but I can’t for the life of me remember if I needed to issue any commands (at or openat) to get it working (actually, i’ve tried a couple of sims that send blank msgs).

Any ideas? Any information would be most appreciated :slight_smile:


What issue :question:


Oops, sorry I should have been more clear :stuck_out_tongue:

I am actually attempting to send SMSs with text in them, but they are coming through on the receiving phone as blank (i.e. no text at all).
When I take that sim & put it into my cell phone, any text that I send is received as expected.

I’ve tried it via the OpenAT api, AT commands and using the discovery tool and they all send blank texts even though I am attempting to send an actual message.

I have sent sms this way before, but it was a different sim & board (the boards are the same, it’s just another of the same board . . .).
My thoughts are that initially I setup something so that the SMSs went through fine and I’ve just forgotten what it was.

Any suggestions would be most appreciated (I hope I’ve clarified myself this time :blush: )


Are you sure it’s really no text at all - or just that the phone can’t display the text?

Are you sending in Text or PDU mode?


I’m sending in Text mode (AT+CMGF? returns 1 to confirm this).

I also tried sending to a couple of different phones and none of them where able to display the message.


Right, it looks like I’ve got somewhere with this.
I was able to find another sim that ‘worked’ that was in an older test board.

Through a series of tests (i.e. old sim in current board works, current sim in old board doesn’t etc.).

What I was able to observe was that the SIM that worked had a config like so:

+CSMP: 1,167,0,0

Whereas the Sim that didn’t work looked like:

+CSMP: 1,167,0,12

My understanding is that the 12 represents the encoding.

So for a work-around for the moment is to execute this on start-up (at the proper time of course :slight_smile: )

AT+CSMP=1, 167, 0, 0

Which works (although might not be the most elegant).

Is anybody able to shed any more light on the subject?


Yes I had this problem with SIMS from a carrier roaming on the vodafone New Zealand network. Vodafone SIMs are fine, roaming SIMs SMS are blank as you say, thank you, you provide a solution!


Again, have you determined if they are actually blank (ie, no content at all), or if it’s just that the phone is not able to display the content…?


Hi awneil, sorry for the delay in replying; been a bit busy :slight_smile:

From my point of view this is a solved issue i.e. changing the encoding meant that the messages were displayed on the phone end (and thus makes it usable).

I would dare venture that this would indicate that it wasn’t a blank message but a message that the phone couldn’t display (as you had suggested).

I’m not to sure how I could 100% confirm this nor can I spend to much time on this as there are ‘more pressing things’ to be developed : P
But if anyone does have any suggestions or ideas that I could (quickly) try out, feel free to pass them on and i can see what I can do.