USSD Commands returning NO CARRIER

[nmvictor]

Hi guys, I have a Huwaei modem(E175). I am programatically(via Java) sending commands to the modems serial port (/dev/ttyUSB0) and things seem to be ok except when I started handling the USSD commands, I simply get the response ERROR / NO CARRIER from the modem depending on how I have sent the USSD command(See below for details). I understand that we have data mode and command mode, what I don't understand is how to explicitly switch between the modes. I would also like to know the detailed meaning of NO CARRIER, does it call for my explicit registration into a GSM network, or what is NO CARRIER supposed to mean in this context? Or is their something I am supposed to do before a USSD session, because if its the network, I am able to send SMS with the modem without the NO CARRIER response. Please help, if you know the workaround, I'd appreciate. A section of the outputs of my program are pasted below.

When sending the USSD command using AT+CUSD:

Submitted AT command: AT+CMGF=1

OK

Submitted AT command: AT+CGREG?

+CGREG: 0,1

OK

Submitted AT command: AT+CUSD=1,"*144#"

ERROR

If i try to send USSD using ADT, i get the NO CARRIER response.

Successfully opened the serial port /dev/ttyUSB0
Submitted AT command: AT+CMGF=1

OK

Submitted AT command: AT+CGREG?

+CGREG: 0,1

OK

Submitted AT command: ATD*144#

NO CARRIER

Note: *144# is the USSD code used to check balance with my SIM Operator.

[ginggs]

AT+CUSD=1,"*144#"

Try:
AT+CUSD=1,"*144#",15

Submitted AT command: ATD*144#

NO CARRIER

This is to be expected, sending a USSD command and dialling are actually two different operations, it's just that most handsets use the call or green button to send USSD as well as make a call.

[nmvictor]

Thanks for the reply. I have tried with that but I still get the ERROR response.

Successfully opened the serial port /dev/ttyUSB0
Submitted AT command: AT+CMGF=1

OK

Submitted AT command: AT+CGREG?

+CGREG: 0,0

OK

Submitted AT command: AT+CUSD=1,"*144#",15

ERROR

Submitted AT command: ATi6

Manufacturer: huawei
Model: E160
Revision: 11.609.06.02.94
IMEI: 351596037574078
+GCAP: +CGSM,+DS,+ES

OK

nmvictor@nmvictors-linuxbox:~$

I wish this could work, Im so close with my application, save for this part.

[ginggs]

Manufacturer: huawei
Model: E160

Aha! This modem requires USSD commands to be PDU encoded. I'll post some info if I can find it.
Take it away, GreGorGy!

[GreGorGy]

I have posted this before but can't find where. Here is a little bit about PDUs.

Lemme quickly find the PDU for *141#

EDIT: found
AT+CUSD=1,"AA182C3602",15

[GreGorGy]

For *144#, use:

AT+CUSD=1,"AA188D3602",15


I have a quick PHP script that goes PDU <==> Text but cannot vouch for its accuracy or anything else - haven't even bothered refactoring the code so its just a quick thing that might help. Save as a PHP (dopdu.php) and run from browser.

<?php
$PDUin = "";
$PDUout = "";
if (isset($_REQUEST["PDUin"]))
	{
	$PDUin = $_REQUEST["PDUin"];
	}
if ($PDUin != "")
	{
	$PDUout = '<BR>Last PDU=<B>'.PtoT($PDUin).'</B>';
	}
	
$Textin = "";
$Textout = "";
if (isset($_REQUEST["Textin"]))
	{
	$Textin = $_REQUEST["Textin"];
	}
if ($Textin != "")
	{
	$Textout = '<BR>Last Text=<B>'.TtoP($Textin).'</B>';
	}

function PtoT($pdu)
	{
	$hexlen = (strlen($pdu)/2) - 1;
	$hexes = array();
	for ($i = 0; $i <= $hexlen; $i++)
		{
		$hexes[] = substr("00000000".base_convert((substr($pdu,($i*2), 2)),16,2),-8);
		}
	$LeftOver = "";
	$Take = 7;
	$FullBin = "";
	for ($i=0 ; $i<= $hexlen ; $i++)
		{
		$rhs = 0 - $Take;
		$FullBin .= substr($hexes[$i] , $rhs).$LeftOver;
		$lhs = 8-$Take;
		$LeftOver = substr($hexes[$i] ,0, $lhs);
		$Take = $Take-1;
		if ($Take == 0) {$Take = 7;}
		if (strlen($LeftOver) == 7)
			{
			$FullBin .= $LeftOver;
			$LeftOver = "";
			}
		}
	$chrnum = array();
	while ($FullBin != "")
		{
		$chrnum[] = chr(bindec(substr($FullBin,0,7)));
		$FullBin = substr($FullBin,7);
		}
	
	return implode("",$chrnum);
	}

function TtoP($text)
	{
	$bins = str_split($text);
	foreach ($bins as $k=>$v)
		{
		$bins[$k] = substr("0000000".base_convert(ord($v),10,2) , -7);
		}
	$hexes = array();
	$maxbins = count($bins) - 1;
	for ($i = 0 ; $i <= $maxbins ; $i++)
		{
		if ($i == $maxbins)
			{
			$hexes[] = substr("00000000".$bins[$i] , -8);
			}
		else
			{
			$hl = strlen($bins[$i]);
			if ($hl > 0)
				{
				$steal = $hl - 8;
				$hexes[] = substr($bins[$i+1],$steal).$bins[$i];
				$bins[$i+1] = substr($bins[$i+1],0,7+$steal);
				}
			}
		}
	$pdu = array();
	foreach ($hexes as $v)
		{
		if ($v != "00000000")
		{ $pdu[] = substr("0".strtoupper(base_convert($v, 2, 16)),-2); }
		}
	return implode("", $pdu);
	}

?>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
	"http://www.w3.org/TR/html4/loose.dtd">
<HTML LANG="en">
<HEAD>
	<META HTTP-EQUIV=CONTENT-TYPE CONTENT="text/html; charset=utf-8">
	<TITLE>PDU in and out</TITLE>
	<META NAME="generator" CONTENT="BBEdit 9.6">
</HEAD>
<BODY>
<FORM METHOD="post" ACTION="dopdu.php">
Enter PDU:<BR>
<TEXTAREA NAME="PDUin" ROWS=5 COLS=50><?php echo $PDUin; ?></TEXTAREA><?php echo $PDUout; ?><BR><BR>
Enter TEXT:<BR>
<TEXTAREA NAME="Textin" ROWS=5 COLS=50><?php echo $Textin; ?></TEXTAREA><?php echo $Textout; ?><BR><BR>
<INPUT TYPE="submit" VALUE="Decode / Encode">
</FORM>

</BODY>
</HTML>

[nmvictor]

I have tried with both this codes:

AT+CUSD=1,"AA182C3602",15

and

AT+CUSD=1,"AA188D3602",15

and it works but only gets me the OK response. Thanks for that, however, I am still not getting the Current balance response, despite keeping the code that checks & fetches the response in a while loop that lasts 2 mins. Is their a step am missing? JJust to mention, I am coding with java.

[GreGorGy]

I want you to consider the following session, bearing in mind that Huaweis do send unsolicited data all the time (for diagnostics, etc). I am on Cell C and will send the USD *101# (check balance). Things in BOLDRED are instructions I am sending to the modem. Things in BOLDGREEN are the modems direct responses to my commands.

ATI

Manufacturer: huawei
Model: E1820
Revision: 11.831.03.00.00
IMEI: --
+GCAP: +CGSM,+DS,+ES

OK

^BOOT:31355834,0,0,0,99

at+cusd=1,"AA182C3602",15

OK

^CSNR:-99,-14

^RSSI:9

+CUSD: 0,"C2303BEC1E97413D90140473C1602050110F4FCBF320729 85ED6C1622F58EC2583CD602EA3BC5C0611C3F430A80792E16 4AE180CD414BA1A",15

^CSNR:-99,-14

^RSSI:9

Look at the blue - unsolicited stuff. That bold blue line starting +CUSD is the response from the operator to my USSD, which you need to pick up. See that rubbish in the "" - it is a PDU response. My php page translates that as:

Balance = R 0.00 Expiry date:01/01/2030.Free Data = 282.10 MB.

See how the month-end balance on cell c is used up

[nmvictor]

Thanks, I got all your saying and I appreciate you information. I apologize for my nagging, but my real problem seems to be picking the bold blue line, which is the operators response to my USSD command, I am only able to pick the green responses from the modem. Please help me past this, and thanks in advance for your patience with me.

[GreGorGy]

Hi nmvictor

I am unfamiliar with java and therefore cannot answer how you would do this. Do you get those unsolicited responses at all? In my app, I tell it to read every line of information from the modem. If the line matches an instruction I have sent, I discard it. If the line matches the information codes (RSSI, BOOT, DSFLOW, etc) I handle it accordingly. If the line starts with a response I am expecting from, say, a USSD, I look out for the line beginning "+CUSD" and then I split it into an array based on the comma. From that array, I find the response and handle it.

ginggs and I have both suffered through this process so we have the patience but not necessarily the complete know how for your programming situation.

[nmvictor]

Do you get those unsolicited responses at all?

Thanks again.To answer the above question, I'd say No. I don't get unsolicited responses in normals situation, when I send a command, in my case its the modem response that gets back. The responses prefixed with ^ don't show, I don't know if its because I'm not letting the thread run long enough to capture them, but like I said, I have the check and fetch code wrapped in a while loop to run for 2 mins, reading every possible line and if any, appending it to a StringBuilder. I could try to make the time longer and get back with the results. On the other hand, are the unsolicited response a feature that could be disabled? Please let me know. Thanks a lot GreGorGy, and ginggs, I am not taking your patience for granted.

[GreGorGy]

You're definitely gonna have to give it a little longer to respond. To disable the ^ responses Huawei only:

AT^CURC=0

(=1 reenables)

Greg

[nmvictor]

Hi, I have been doing some Goooogling and I stumbled upon some info that Huawei modems attach to 3 ports[http://ubuntuforums.org/showthread.php?t=1017630&page=3 See the last post on that thread], in case of linux (/dev/ttyUSB0, /dev/ttyUSB1 and /dev/ttyUSB2). I have tried opening these ports and sending commands to the three ports and they all work save for /dev/ttyUSB2. Either way, I have an extra port, Im thinking I could have a thread monitoring /dev/ttyUSB1 for these "unsolicited responses and anything from the network, then have /dev/ttyUSB0 for normal AT commands and responses operation. Am telling you all these just in case you have a better suggestion. Back to coding, I'll check in just in case you post that suggestion or anything new. I appreciate your help through this, I nagged a lot but bottom-line, I am learning more which I owe to you and your patience. Thanks again.

[thandabantu]

Hie people i need i best modem for my internate caffe how do i get it?

[GreGorGy]

Hie people i need i best modem for my internate caffe how do i get it?

yuu bye it att the voddacom shoppe.

You will find this an expensive way to run an internate caffe