In order to send SMS messages containing ringtones, wallpapers, WAP push or VCards, the content needs to be sent as a binary message. In order to send a binary message to a phone the User Data Header (UDH) construct must be used. The UDH is a short hexadecimal code when received by the handset indicates the type of content contained in the binary message and how to process it. In addition to the UDH, setting the correct Data Coding Scheme value,
4 in the case of a Binary SMS is also required.
Most UDH’s are for Nokia manufacture/branded phones and the details for constructing Smart Messages is documented in their Smart Messaging Specification. Sony Ericsson have a similar message structure that is compatible with their handsets documented at http://developer.sonymobile.com.
Due to smartphone and data access penetration, binary messages are rarely used and are not typically supported on the iPhone.
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