Text formatting with EMS

This entry is part 12 of 17 in the series Sending out an SMS

We have seen how you can use the User Data Header (UDH) in an SMS message to combine several SMS messages into one bigger one. Here is an other application of the UDH:

Text formatting in SMS

Remember that the UDH consists of Information Elements (IE) that each have the following structure

Length Value Description
1 octet IEI Information Element Identifier. This determines what this IE is about.
1 octet IE length The length of the data belonging to this IE in octets.
n octets IE data Meaning of the content varies per IEI.

 

The text formatting is controlled by just one IE. Here is a description:

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Sending a bookmark over SMS

Another use for SMS is configuring phones over the air (OTA). There are elaborate standard specifications written by the WAP Forum (now Open Mobile Alliance) and somewhat proprietary standards developed by Nokia and Ericsson.

Today I’ll show in detail how to send a bookmark according the Nokia / Ericsson specification. The specification is somewhat older, it dates from September 2001, but it seems almost all Nokia and many Ericsson devices still support this.

The bookmark is described in an XML file like the following:

< ?xml version="1.0"?>
< !DOCTYPE CHARACTERISTIC-LIST SYSTEM "settings.dtd">
<characteristic -LIST>
   </characteristic><characteristic TYPE="BOOKMARK">
       <parm NAME="NAME" VALUE="Mobile Tidings"/>
       <parm NAME="URL" VALUE="http://mobiletidings.com"/>
   </characteristic>

As before we send this XML document using an unconfirmed push. Here are the layers we need to implement:

  • the XML document needs to be WBXML encoded and
  • the WBXML need to be wrapped in a WSP (Wireless Session Protocol) Push PDU
  • this needs to be wrapped in a WDP (Wireless Datagram Protocol) packet
  • this needs to be sent inside an SMS

As always we start with the AT command that is used to send the bookmark and analyze in detail how this AT command was constructed:

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