Message Types

This describes different types of messages traced on different interfaces.

The interfaces that BSC uses are the A interface, the Abis interface, the Pb interface, the Um interface, and the Gb interface. Table 1 and Table 2 describes different types of messages traced on the interfaces.

**Table 1** Messages on different interfaces in CS domain
Interface	Message	Message Type	Meaning
A interface	BSSAP message on the A interface	BSSMAP message	Base Station Subsystem Management Application Part message. The BSSAP message on the A interface is defined by the GSM 08.08 protocol.
		DTAP message	Direct Transfer Application Part message. DTAP messages include the messages on CC and MM layers. These messages are transparently sent on the A interface.
		PAGING message	Paging message
		Other messages	BSSAP messages on the A interface except the three types of messages above.
	SCCP message on the A interface	SCCP message on the A interface	Signaling Connection Control Part message
	MTP3 message on the A interface	SNM message	Signaling Network Management message, component of the MTP3 message
		SCCP message	Signaling Connection Control Part message
		ISUP message	Integrated Services Digital Network User Part message
		SLT message	Signaling Link Test message
		TUP message	Telephone User Part message
		MT message	Maintenance Test message
		UNKNOWN message	Other messages
		L2_GHANGE message	Internal control command message on the MTP2 and MTP3 layers
	MTP2 message on the A interface	LSSU message	Link Status Signaling Unit message
	MTP2 message on the A interface	MSU message	Message Signaling Unit message
	SCTP message on the A interface	CTRL message	Control message
		DATA message	Data message
		HB message	Heartbeat message
	M3UA message on the A interface	MNG message	Management message
		TR message	Transfer message
		SSNM message	Signaling System No.7 Network Management message
		ASPSM message	ASP State Maintenance message
		ASPTM message	ASP Traffic Maintenance message
		RKM message	Routing Keyword Message
Abis interface	RSL message on the Abis interface	DCM message	Dedicated Channel Management message
		CCM message	Common Channel Management message
		RLM message	Radio Link Management message
		TRXM message	TRX Management message
	OML message on the Abis interface	Common message	Common message
	ESL message on the Abis interface EML message on the Abis interface	OM message	OM message
	LAPD message on the Abis interface	-	-
Um interface	Message on the Um interface	PAGING message	PAGING message
Um interface	Message on the Um interface	Other messages	Messages on the UM interface except the PAGING message.
User interface	User message	-	-
BSC-CBC interface	BSC-CBC interface message	-	-
-	Group call messages	-	-
-	IP messages	-	-
Pb interface	Application message on the Pb interface	PAGING message	Paging message
		CONFUSION message	CONFUSION message
		PCIC check message	Packet Circuit Identity Code of the Pb interface
		Other messages	pplication messages on the Pb interface except the three types of messages above
	LAPD message on the Pb interface	-	-

**Table 2** Messages on different interfaces in PS domain
Interface	Message	Message Type	Meaning
Gb interface	SIG message on the Gb interface	-	-
Gb interface	PTP message on the Gb interface	-	-
Um interface	Um interface message	NULL message	Null paging message
		DATA message	Data block message
		SYS message	System message
		DUMMY message	Invalid message