SIST ETS 300 603/A1 E1:2003

SIST ETS 300 603/A1 E1:2003 is an ETSI amendment to the GSM Phase 2 interworking standard for packet switched data transmission services between a PLMN and a PSPDN/ISDN. It updates how access is handled when a PH supports only X.31 case B and when a subscriber has more than one basic packet mode service. The document is aimed at people who configure, operate, or interconnect mobile and fixed networks.

What does SIST ETS 300 603/A1 E1:2003 specify?

SIST ETS 300 603/A1 E1:2003 specifies changes to ETS 300 603 (1994), especially the parts that control packet access, roaming interworking, and user-rate handling. The amendment concentrates on X.31 case A and case B, on the use of a service number, and on the way the HPLMN and PLMN handle calls for packet-mode services.

The technical changes are applied in Clause 3, subclauses 7.2, 8.3.1, 8.3.2, 8.4.1 and 8.4.2, plus Figure 5/GSM09.06. In practice, the document tells implementers where the call is set up, who performs conversion, and how the network behaves when the subscriber and the visited network support different packet rates or access cases.

What are the key requirements of SIST ETS 300 603/A1 E1:2003?

• Clause 3 adds separate definitions for GSM packet mode services using X.31 case A and X.31 case B. Case A uses a circuit connection, while case B uses a packet connection. For implementers, this fixes the access method that must be used at the network edge.

• Clause 3 also defines the service number. SIST ETS 300 603/A1 E1:2003 makes this a special E.164 number in the HPLMN that tells the home network to perform case A/B conversion and translate the number to the PH’s actual E.164 number. In practice, this is the number the subscriber dials to reach a case B access path.

• Subclause 7.2 states that a PH or an PSPDN port is treated as part of the ISDN or the PSPDN, as shown in Figures 1 and 2/GSM09.06. It also allows PHs that support only X.31 case B, provided the PLMN and fixed network operators agree on case B signaling. This matters because roaming access depends on coordination between mobile and fixed-network signaling.

• Subclauses 7.2, 8.3.1 and 8.3.2 require the GSM HPLMN or the PLMN to handle X.31 case A/B conversion when the PH supports only case B. In practice, the network must perform the translation so that the call can proceed without the PH needing to support both access styles.

• Subclause 8.4.1 sets the rule for more than one subscribed basic packet mode service in the HLR: the highest subscribed user rate is used. If the VPLMN does not support that rate, the call fails. This means subscription data and visited-network capability must match, or the call will not complete.

• Subclause 8.4.2 says the applicable scenarios are those in Figures 1 to 3, and that the call is handled like any other data call for an MS in the VPLMN, following the dial-out case in Figures 4 and 5/GSM09.06. For operators, this links packet-mode roaming to the standard data-call handling path.

What terms does SIST ETS 300 603/A1 E1:2003 define?

• PLMN - the Public Land Mobile Network, which is the mobile network side of the interworking arrangement.
• PSPDN/ISDN - the packet-switched public data network or integrated services digital network on the fixed-network side.
• X.31 case A - the access case that uses a circuit connection to reach packet service.
• X.31 case B - the access case that uses a packet connection to reach packet service.
• service number - the special HPLMN E.164 number used to trigger case A/B conversion for a case B PH.
• HPLMN - the home network that translates the service number and performs the needed conversion.
• VPLMN - the visited network where the roaming subscriber is currently attached.
• BC-IE - the bearer capability information element whose parameters identify whether access is circuit mode or packet mode.

Who uses SIST ETS 300 603/A1 E1:2003?

SIST ETS 300 603/A1 E1:2003 is used by GSM and PLMN network engineers, ISDN interworking teams, and fixed-network operators who configure packet access and roaming behavior. It is also relevant to quality managers and buyers who need to check whether equipment or network integration supports X.31 case B, service-number handling, and user-rate selection in roaming scenarios.

What changed in SIST ETS 300 603/A1 E1:2003 from the previous edition?

SIST ETS 300 603/A1 E1:2003 is Amendment 1 to ETS 300 603 (1994). The amendment aligns the standard with changes to GSM Technical Specification GSM-TS 09.06 from version 4.4.1 to version 4.5.0 and updates the text on X.31 case B support, case A/B conversion, and multiple subscribed basic packet mode services. It also replaces Figure 5/GSM09.06 and updates the affected pages listed in the foreword.

Which standards are used with SIST ETS 300 603/A1 E1:2003?

• ETS 300 603 (1994) - the base standard that this amendment modifies.
• ETS 300 099 - the packet service access reference used in the definitions of X.31 case A and case B.
• GSM-TS 09.06 - the GSM technical specification whose changes are mirrored by this amendment.

What does the SIST ETS 300 603/A1 E1:2003 document contain?

The document contains amendment text rather than a full standalone technical specification. It revises definitions in Clause 3, rewrites parts of subclause 7.2, adjusts call-handling rules in 8.3.1 and 8.3.2, and changes the user-rate rule in 8.4.1. It also replaces Figure 5/GSM09.06 with a roaming diagram for Home Country and Visited Country that shows dial-in and dial-out behavior for PH case B. This makes the amendment useful for implementation, interworking design, and troubleshooting of packet-mode roaming calls.