Wireless Session Protocol (WSP)

The Wireless Session Protocol offers the HTTP request-response paradigm, and in addition it offers a new service named Wap Push, allowing applications in the network to push (unsolicited) data to a push-enabled application on the mobile device.

The Wireless Session Protocol started with the knowledge that many header names and values in the Hyper_Text_Transfer_Protocol are fixed strings. With efficient over-the-air usage of the bandwidth in mind, WSP attempts at encoding these fixed strings in a compact binary manner. This way, the header cache-control: no-cache can be encoded in 2 bytes: one for the header name (cache-control) and one for its value (no-cache).

There are 2 types of WSP:

On a protocol level, CO-WSP relies upon WTP for the added functionality. With CL-WSP, the WTP layer is reduced to a one-byte transaction identifier, which is part of WSP as the 1st byte. This way it is still possible in WTP to match a response with a request (same WSP transaction identifier).

The word "connection" in connection-oriented WSP has nothing to do with the actual bearer connection. In fact CO-WSP might be seen as a more stateful and elaborate version of CL-WSP, where the latter provides only basic functionality.


In the early days of mobile Internet (access to Internet-like network services with a handheld device on a wireless network), it was already understood that bandwidth was a costly resource, and that round-trips were typically significantly longer than on classic computer networks. Both yielded an efficient protocol family created at the WAP Forum. The WAP Forum defined a protocol family for enabling Internet-like and Internet-based serviced to be accessible on mobile devices with limited capabilities and resources, being part of a wireless network.

One of the goals of the WAP Forum was to define a set of protocols which could offer Hyper_Text_Transfer_Protocol like transport in a more efficient manner. This resulted in the Wireless Session Protocol (WSP).

Protocol dependencies

The WAP transport protocol stack is shown below:

WapProtocolFamily/WAP<span data-escaped-char>_</span>Transport<span data-escaped-char>_</span>Protocol<span data-escaped-char>_</span>Stacks.jpg

Depending on the protocol stack, 4 different standard WDP (UDP) ports have been defined: 9200, 9201, 9202 and 9203. WSP can run on other ports too.

Example traffic

No.     Time        Source                Destination           Protocol
    669 193.049760                SMPP

WSP Push (0x06) (WBXML 1.2, Public ID: "-//WAPFORUM//DTD SI 1.0//EN (Service Indication 1.0)")

Frame 669 (191 bytes on wire, 191 bytes captured)
    Arrival Time: Jan  7, 2005 11:11:29.444839000
    Time delta from previous packet: 193.049760000 seconds
    Time since reference or first frame: 193.049760000 seconds
    Frame Number: 669
    Packet Length: 191 bytes
    Capture Length: 191 bytes
Ethernet II, Src: 00:0b:cd:31:a1:2b, Dst: 00:40:f4:61:36:52
    Destination: 00:40:f4:61:36:52 (CameoCom_61:36:52)
    Source: 00:0b:cd:31:a1:2b (CompaqHp_31:a1:2b)
    Type: IP (0x0800)
Internet Protocol, Src Addr: (, Dst Addr: (
    Version: 4
    Header length: 20 bytes
    Differentiated Services Field: 0x00 (DSCP 0x00: Default; ECN: 0x00)
        0000 00.. = Differentiated Services Codepoint: Default (0x00)
        .... ..0. = ECN-Capable Transport (ECT): 0
        .... ...0 = ECN-CE: 0
    Total Length: 177
    Identification: 0x01a1 (417)
    Flags: 0x04 (Don't Fragment)
        0... = Reserved bit: Not set
        .1.. = Don't fragment: Set
        ..0. = More fragments: Not set
    Fragment offset: 0
    Time to live: 128
    Protocol: TCP (0x06)
    Header checksum: 0xe1d5 (correct)
    Source: (
    Destination: (
Transmission Control Protocol, Src Port: 1054 (1054), Dst Port: 10001 (10001),
 Seq: 48, Ack: 48, Len: 137
    Source port: 1054 (1054)
    Destination port: 10001 (10001)
    Sequence number: 48    (relative sequence number)
    Next sequence number: 185    (relative sequence number)
    Acknowledgement number: 48    (relative ack number)
    Header length: 20 bytes
    Flags: 0x0018 (PSH, ACK)
        0... .... = Congestion Window Reduced (CWR): Not set
        .0.. .... = ECN-Echo: Not set
        ..0. .... = Urgent: Not set
        ...1 .... = Acknowledgment: Set
        .... 1... = Push: Set
        .... .0.. = Reset: Not set
        .... ..0. = Syn: Not set
        .... ...0 = Fin: Not set
    Window size: 64081
    Checksum: 0x66e6 (correct)
Short Message Peer to Peer, Command: Submit_sm, Seq: 19, Len: 137
    Length    : 137
    Operation : Submit_sm (0x00000004)
    Sequence #: 19
    Service type: (Default)
    Type of number (originator): Unknown (0x00)
    Numbering plan indicator (originator): ISDN (E163/E164) (0x01)
    Type of number (recipient): National (0x02)
    Numbering plan indicator (recipient): ISDN (E163/E164) (0x01)
    Recipient address: 0123456789
    .... ..00 = Messaging mode: Default SMSC mode (0x00)
    ..00 00.. = Message type  : Default message type (0x00)
    01.. .... = GSM features  : UDHI indicator (0x01)
    Protocol id.: 0x00
    Priority level: GSM: None      ANSI-136: Bulk         IS-95: Normal (0x00)
    Scheduled delivery time: Immediate delivery
    Validity period: SMSC default validity period
    .... ..00 = Delivery receipt  : No SMSC delivery receipt requested (0x00)
    .... 00.. = Message type      : No recipient SME acknowledgement requested (0x00)
    ...0 .... = Intermediate notif: No intermediate notification requested (0x00)
    .... ...0 = Replace           : Don't replace (0x00)
    Data coding: 0xf5
        SMPP Data Coding Scheme: Unknown (0xf5)
        GSM SMS Data Coding
        1111 .... = DCS Coding Group for SMS: SMS DCS: Data coding / message class (0x0f)
        .... 01.. = DCS Character set: 8-bit data (0x01)
        .... ..01 = DCS Message class: Class 1 - ME specific (0x01)
        GSM CBS Data Coding
        1111 .... = DCS Coding Group for CBS: SMS DCS: Data coding / message class (0x0f)
        .... 01.. = DCS Character set: 8-bit data (0x01)
        .... ..01 = DCS CBS Message class: Class 1 - User defined (0x01)
    Predefined message: 0
    Message length: 94
GSM Short Message Service User Data
    UDH Length: 6
        IE Id: SMS - Application port addressing scheme, 16 bit address (0x05):
         source port 9200, destination port 2948
            Destination port: 2948
            Source port: 9200
Wireless Session Protocol, Method: Push (0x06), Content-Type: application/vnd.wap.sic
    Transaction ID: 0xd0
    PDU Type: Push (0x06)
    Headers Length: 1
    Content-Type: application/vnd.wap.sic
WAP Binary XML, Version: 1.2, Public ID: "-//WAPFORUM//DTD SI 1.0//EN (Service Indication 1.0)"
    Version: 1.2 (0x02)
    Public Identifier (known): -//WAPFORUM//DTD SI 1.0//EN (Service Indication 1.0) (0x00000005)
    Character Set: utf-8 (0x0000006a)
    String table: 0 bytes
    Data representation
        Level | State | Codepage | WBXML Token Description         | Rendering
            0 | Tag   | T   0    |   Known Tag 0x05           (.C) |  <si>
            1 | Tag   | T   0    |   Known Tag 0x06           (AC) |    <indication
            1 |  Attr | A   0    |   Known attrStart 0x0C          |      href='http://'
            1 |  Attr | A   0    | STR_I (Inline string)           |        'src.miel.com/imags/
            1 |  Attr | A   0    |   Known attrStart 0x07          |      action='signal-medium'
            1 | Tag   | T   0    | END (attribute list)            |    >
            1 | Tag   | T   0    | STR_I (Inline string)           |    'Merry xmas !!!! JO JO JO'
            1 | Tag   | T   0    | END (Known Tag 0x06)            |    </indication>
            0 | Tag   | T   0    | END (Known Tag 0x05)            |  </si>


The WSP dissector is fully functional, with the restriction that the Expect, Retry-After, Cookie and Set-Cookie headers are not yet decoded.

Wireshark also provides WSP statistics. Output looks like:


Preference Settings

There are no preferences for WSP in Wireshark.

Example capture file


Display Filter

A complete list of WSP display filter fields can be found in the display filter reference

Show only the WSP based traffic:


Capture Filter

You cannot directly filter WSP traffic while capturing. However, if you know the transport protocols used (see above), you can filter that way.

External links


Imported from https://wiki.wireshark.org/Wireless_Session_Protocol on 2020-08-11 23:27:34 UTC