Need to send SMSC configuration texts to SIM

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Casper Helenius
New member
Username: Casperhelenius

Post Number: 1
Registered: 01-2011
Posted on Wednesday, January 05, 2011 - 08:40 am:   

Hi guys,

My employer, a major danish discount service provider, wants to be able to send configuration texts to our customers, (re)setting the SMSC number on the SIM.

However, we are having a hard time finding the proper information on how to do this.

Does anyone out there have any valuable links to samples, tutorials, walkthroughs or the likes on how to build the encrypted message?

Oh, before anyone asks, we do have the security code for the SIMs (as we provide the SIMs ourselves)

Best regards,

Casper Helenius
TELMORE, Denmark
Des - NowSMS Support
Board Administrator
Username: Desosms

Post Number: 2811
Registered: 08-2008
Posted on Friday, January 07, 2011 - 08:33 pm:   

Hi Casper,

Are these your SIMs? I ask this because you do need the security code(s) for the SIM, so that you can properly encrypt and sign the message.

This is outside of my area of expertise, but as I understand it, you need to send a SIM update message.

There is a file on the SIM that contains the SMSC address, and this file needs to be updated.

You need to construct an ETSI GSM 11.11/11.14 binary message with a valid security code for encryption. ETSI GSM 03.48 defines the security mechanisms for the encryption of the data.

There's generally UDH (user data header) involved ... 027000. DCS is F6 and PID is 7F. Those are the easy parts ... the tough part is creating the message content to carry out this task. (I mention this part, because if you search this forum using a keyword of 027000 you will find some messages that reference others trying to accomplish similar tasks.)

For the specifications that I referenced above ... you can find them at, or more specifically

NowSMS Support

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