Error codes 540 from Modem

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Chitra Phadke
Posted on Tuesday, December 02, 2008 - 02:56 am:   


I have a NowSMS with a Sierra Wireless Aircard that seems to return an error code of 540 when submitting a SMS to send out.How can I find out more about the error code to debug further?
Des - NowSMS Support
Board Administrator
Username: Desosms

Post Number: 283
Registered: 08-2008
Posted on Tuesday, December 02, 2008 - 02:18 pm:   

Hi Chitra,

Good question. Error code 540 is within the "manufacturer specific" range ... and unfortunately, I don't see it listed in any of the Sierra Wireless documentation that I can find.

So, let's try some of the basics.

First, remove the SIM card from the modem and put it into a mobile phone. Verify that the phone can send and receive SMS messages using the SIM. (If it can't, then there's something wrong with the account associated with the SIM.)

Use the utility software included with the modem and verify that you have a good signal for connecting to the mobile operator.

Go into "Properties" for the modem in the NowSMS "SMSC" list, and change "SMS Access" to "GSM". (If this is a 3G modem, this doesn't necessarily mean that you're going to drop back to the 2G network. This setting means to use the "circuit switched" network instead of the "packet switched" network. Some mobile operators do not have SMS support enabled over the "packet switched" network.)

There is also an issue with some 3G modems that they do not properly read the SMSC address from the SIM card when connected to the 3G network. (In this case, usually you see a CMS ERROR 330.) There are two ways to address this issue:

1.) The easiest way is to temporarily force the modem into 2G mode. Manually edit SMSGW.INI, and under the [Modem - Sierra ...] header add:


(The above tells the modem only to use the 2G/GPRS/EDGE network. When you're done testing, change this to AT+WS46=25, which will tell the modem it can use either the 3G or 2G network.)

2.) Dropping back to the 2G network as described above is not an ideal solution. If the modem is not reading the SMSC address from the SIM in 3G mode, then the best way to deal with this is to manually configure the SMSC address in NowSMS. This SMSC address varies depending upon what operator you are subscribed to.

You can set the SMSC address by manually editing the SMSGW.INI file. Under the section header for the modem configuration (e.g., [Modem - ...], add SMSC=+phonenumber, where "+phonenumber" is the address of the SMSC. Here's a link to a good list of SMSC phone numbers: A more reliable way of determining the correct SMSC number is to put your SIM into a phone, and go through the SMS configuration menus on the phone to determine the currently configured SMSC number. When you enter the SMSC phone number, always start it with a "+" and don't include any other non-numeric characters (no dashes or dots) in the address.

Always restart the gateway service after making a change to the SMSGW.INI file.

If you try setting the SMSC value by manually editing SMSGW.INI ... if the setting doesn't make a difference, always go back in and remove it immediately so that it doesn't confuse things down the road.

NowSMS Support

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