SCKL Format

What is SCKL ?

The SCKL format is developed to deliver binary content to mobile phones independend of the underlying network technology. SCKL is developed by Nokia, and can be used on GSM, CDMA, iDen and TDMA networks. The data is sent in a plain text message which is supported by all networks.

The format of a SCKL message

SCKL messages consits of a header and user data.

The headers specifies to which application port the message have to be send, and includes data for message segmentation and reassembly.

Bytes Description
6 //SCKL string
4 Destination Port number in HEX
4 Source Port number in HEX
2 Message Reference number
2 Number of Segments
2 Number of this segment
Sample of a message with 3 segments:
//SCKL15811581A50301 USERDATA
//SCKL15811581A50302 USERDATA
//SCKL15811581A50303 USERDATA

The user data can be encoded as text or binary. When coded in binary (ringtones and picturemessages), data is encoded in 2digit HEX format. Please note that there has to be a space between the header and the user data.

For instance: //SCKL1581 06050415810000024A3A6115A5999995B080D80400231C934836C26C30C36C511624B30D30DA0C30DB144D8000

Port numbers

The first value in the header specifies the application port number. These port numbers are part of the Wireless Datagram Protocol (WDP). The WDP Port numbers are approved by the Internet Association Authority (IANA).

The following port numbers are currently in use:

Port Number Application
0x1581 Ring Tones
0x1582 Operator Logo
0x1583 Group Logo
0x23F4 vCard
0x23F5 vCalendar
0x23F6 Secure vCard
0x23F7 Secure vCalendar


Sending a ringtone

To send a ringtone, we have to send the data to port 0x1581 of the mobile phone. The ringtone data can be composed with ringtone convert software such as Coding Workshop Ringtone Converter. It is also possible to send a ringtone in RTTTL format using the 'Ringtone' object of the SMS and Pagertoolkit.

The SCKL Data:

//SCKL1581 024A3A6115A5999995B080D80400231C934836C26C30C36C511624B30D30DA0C30DB144D8000

Sending an operator logo

An operator logo is a small icon that is associated with the operator the mobile phone is connected to. The mobile network and country code have to be encoded in the message data.

The SCKL Data:

//SCKL15821582AA0201 3002F4610A00480E010000019FF1FF180000000003301B019C0000000002200A00C400000000024004004200000000004004004000000000F8
//SCKL15821582AA0202 FD44C466492490

Clearing the operator logo

To clear the operator logo, and display the networkname as text, use the following SCKL data:

//SCKL1582 300000000A00000001

Sending a group logo

A Group logo is a small icon that will be associated with certain groups of people. When a member of a caller group rings you, this icon is displayed in the display of the mobile phone. The size of the picture is 72x14 pixels, and has to be black and white.

The SCKL Data:

//SCKL1583 3000480E010000019FF1FF180000000003301B019C0000000002200A00C400000000024004004200000000004004004000000000F840040040000000017440040

Sending a vCard message

To send an electronic business card to a mobile phone, you set the userdata as defined in the vCard standard.

The SCKL Data:

N:John Doe<CR><LF>