Transport

The transport part of the message contains parameters related to the lower level transports. On receive these parameters are filled from the received message. On send these parameters are used by the transports to properly form and route the message.

MTP

The <mtp> transport section describes message parameters specific to MTP. Normally these parameters are just informative for the applications and on new outbound messages are added automatically.

This section may be missing for error reports created higher in the protocol stack or if the SS7 transport is not MTP.

<mtp>
      <LocalPC>101</LocalPC>
      <RemotePC>5000</RemotePC>
      <sls>2</sls>
</mtp> 

Parameters

• LocalPC – Point Code on the local side; DPC for inbound messages, OPC for outbound
• RemotePC – Point Code on the local side; OPC for inbound messages, DPC for outbound
• sls – Signaling Link Selection Code

SCCP

The <sccp> transport describes the SCCP specific parameters. These control how messages are routed to their destination by point code, subsystem or phone number. This section may be missing for error reports created higher in the protocol stack (for example TCAP transaction timeout).

<sccp>
	<CalledPartyAddress>
		<ssn>5</ssn>
		<pointcode>101</pointcode>
		<gt nature="international" plan="isdn">492115000000</gt>
	</CalledPartyAddress>
	<CallingPartyAddress>
		<ssn>0</ssn>
	</CallingPartyAddress>
</sccp>

Parameters

• CalledPartyAddress – SCCP style address of the message's receiver
  • ssn – SubSystem Number of the receiver, usually present, zero if unknown
  • pointcode – Point Code of the receiver, optional
  • gt – Global Title of the receiver, optional, usually a phone number
    • encoding – Encoding scheme of the gt, if not decoded
    • nature – Nature of the gt (national, international, etc.)
    • plan – Numbering plan of the gt (usually isdn)
  • route – Routing indicator, may be by "gt" or "ssn"
• CallingPartyAddress – SCCP style address of the message's sender
  • ssn – SubSystem Number of the sender, usually present, zero if unknown
  • pointcode – Point Code of the sender, optional
  • gt – Global Title of the sender, optional, usually a phone number
    • encoding – Encoding scheme of the gt, if not decoded
    • nature – Nature of the gt (national, international, etc.)
    • plan – Numbering plan of the gt (usually isdn)
  • route – Routing indicator, may be by "gt" or "ssn"

TCAP

The <tcap> transport describes the TCAP specific parameters. These are related to the transactions.

Parameters

• request-type – Type of the TCAP request, may be one of: Begin, Continue, End
• localTID – Local Transaction ID
• remoteTID – Remote Transaction ID

For received transactions (Converter => App.) the received remoteTID needs to be saved and copied to all answers. An unique localTID must be created only for Continue requests.

For transactions created by the application (App. => Converter) the localTID must be assigned uniquely by the application. A remoteTID may be received for Continue requests, in which case it must be saved by the application.

A trasaction may be terminated silently (without actually sending a message to the remote), usually after waiting a while for an error notification. To achieve such a result send !!!!!!!!!!!!!

Addressing

There are several types of addresses that are used to specify at which server and / or mobile station is a message to be delivered. The exact usage depends on the context of the operation that creates the TCAP dialog.

• SCCP Global Titles

The calling or Called Party Global Titles are usually populated with the numbers associated with the network entities (HLR, VLR, MSC, etc) exchanging the messages.

For the sendAuthenticationInfo and updateLocation operations the IMSI of the SIM card is used as Called (for request) or Calling (for response) Party Address.

• TCAP Dialog user information

Some operations add User Information in the TCAP dialog. These allow addressing the mobile stations by their IMSI while SCCP is used to route the message to the network entity (MSC, VLR, HLR) where the user is roaming or registered.

• Parameters embedded in requests

Most messages include specific parameters to identify the network elements. The message as a whole is routed by SCCP GT but internally the systems are using these parameters for database access or forwarding the information.

All these types of addressing may be present in a single message.