QSIG is an ISDN

Integrated Services Digital Network

Integrated Services Digital Network is a set of communications standards for simultaneous digital transmission of voice, video, data, and other network services over the traditional circuits of the public switched telephone network...

 based signaling protocol

Signaling protocol

A signaling protocol is a type of protocol used to identify signaling encapsulation. Signaling is used to identify the state of connection between telephones or VOIP terminals . The following is a list of signaling protocols:...

 for signaling between private branch exchanges (PBXs) in a Private Integrated Services Network (PISN). It makes use of the connection-level Q.931

Q.931

ITU-T Recommendation Q.931 is ISDN's connection control protocol, roughly comparable to TCP in the Internet Protocol stack. Q.931 doesn't provide flow control or perform retransmission, since the underlying layers are assumed to be reliable and the circuit-oriented nature of ISDN allocates...

 protocol and the application-level ROSE

Remote operations service element protocol

The Remote Operations Service Element is the OSI service interface, specified in , that provides remote operation capabilities, allows interaction between entities in a distributed application, and upon receiving a remote operations service request, allows the receiving entity to attempt the...

 protocol. ISDN "proper" functions as the physical link layer.

QSIG was originally developed by Ecma International

Ecma International

Ecma International is an international, private non-profit standards organization for information and communication systems. It acquired its name in 1994, when the European Computer Manufacturers Association changed its name to reflect the organization's global reach and activities...

, adopted by ETSI and is defined by a set of ISO

International Organization for Standardization

The International Organization for Standardization , widely known as ISO, is an international standard-setting body composed of representatives from various national standards organizations. Founded on February 23, 1947, the organization promulgates worldwide proprietary, industrial and commercial...

 standard documents, so is not owned by any company. This allows interoperability between communications platforms provided by disparate vendors.

QSIG has two layers, called BC (basic call) and GF (generic function). QSIG BC describes how to set up calls between PBXs. QSIG GF provides supplementary services for large-scale corporate, educational, and government networks, such as line identification, call intrusion and call forwarding

Call forwarding

Call forwarding , in telephony, is a feature on some telephone networks allowing an incoming call to a called party to be redirected to a third party. For example, the third party may be a mobile telephone, voicemail box or other telephone number where the desired called party is situated. It was...

. Thus for a large or very distributed company that requires multiple PBXs, users can receive the same services across the network and be unaware of the switch that their telephone is connected to. This greatly eases the problems of management of large networks.

QSIG will likely never rival each vendor's private network protocols, but it does provide an option for a higher level of integration than that of the traditional choices.

List of QSIG standards

Note: This list is not complete. See the "source" after the list for more information.

• ECMA-143 - Private Integrated Services Network (PISN) - Circuit Mode Bearer Services - Inter-Exchange Signalling Procedures and Protocol (QSIG-BC), Basic Call,
  International and European Versions: ISO/IEC 11572, ETSI EN 300 172
• ECMA-165 - Private Integrated Services Network (PISN) - Generic Functional Protocol for the Support of Supplementary Services - Inter-Exchange Signalling Procedures and Protocol (QSIG-GF),
  International and European Versions: ISO/IEC 11582, ETSI ETS 300 239
• ECMA-164 - Private Integrated Services Network (PISN) - Inter-Exchange Signalling Protocol - Name Identification Supplementary Services (QSIG-NA),
  International and European Versions: ISO/IEC 13868, ETSI ETS 300 238
• ECMA-174 - Private Integrated Services Network (PISN) - Inter-Exchange Signalling Protocol - Call Diversion Supplementary Services (QSIG-CF),
  International and European Versions: ISO/IEC 13873, ETSI ETS 300 257
• ECMA-178 - Private Integrated Services Network (PISN) - Inter-Exchange Signalling Protocol - Call Transfer Supplementary Service (QSIG-CT),
  International and European Versions: ISO/IEC 13869, ETSI ETS 300 261

Source : ECMA - list of standards (search the list for PISN to find all QSIG related standards at ECMA)

QSIG basically uses ROSE

Remote operations service element protocol

The Remote Operations Service Element is the OSI service interface, specified in , that provides remote operation capabilities, allows interaction between entities in a distributed application, and upon receiving a remote operations service request, allows the receiving entity to attempt the...

 to invoke specific supplementary service at the remote PINX. These ROSE

Remote operations service element protocol

The Remote Operations Service Element is the OSI service interface, specified in , that provides remote operation capabilities, allows interaction between entities in a distributed application, and upon receiving a remote operations service request, allows the receiving entity to attempt the...

 operations are coded in a Q.931

Q.931

ITU-T Recommendation Q.931 is ISDN's connection control protocol, roughly comparable to TCP in the Internet Protocol stack. Q.931 doesn't provide flow control or perform retransmission, since the underlying layers are assumed to be reliable and the circuit-oriented nature of ISDN allocates...

FACILITY info element. Here a list of QSIG opcodes:

opcode	supplServ	defining ECMA
0	callingName	ECMA-164
1	calledName	ECMA-164
2	connectedName	ECMA-164
3	busyName	ECMA-164
4	pathReplacePropose	ECMA-176
5	pathReplaceSetup	ECMA-176
6	pathReplaceRetain	ECMA-176
7	callTransferIdentity	ECMA-178
8	callTransferAbandon	ECMA-178
9	callTransferInitiate	ECMA-178
10	callTransferSetup	ECMA-178
11	callTransferActive	ECMA-178
12	callTransferComplete	ECMA-178
13	callTransferUpdate	ECMA-178
14	subaddressTransfer	ECMA-178
15	activateDiversionQ	ECMA-174
16	deactivateDiversionQ	ECMA-174
17	interrogateDiversionQ	ECMA-174
18	checkRestriction	ECMA-174
19	callRerouteing	ECMA-174
20	divertingLegInformation1	ECMA-174
21	divertingLegInformation2	ECMA-174
22	divertingLegInformation3	ECMA-174
23	cfnrDivertedLegFailed	ECMA-174
27	ccnrRequest	ECMA-186
28	ccCancel	ECMA-186
29	ccExecPossible	ECMA-186
30	ccPathReverse	ECMA-186
31	ccRingout	ECMA-186
32	ccSuspend	ECMA-186
33	ccResume	ECMA-186
34	callOfferRequest	ECMA-192
35	doNotDisturbActivateQ	ECMA-194
36	doNotDisturbDeactivateQ	ECMA-194
37	doNotDisturbInterrogateQ	ECMA-194
38	doNotDsturbOverrideQ	ECMA-194
39	doNotDisturbOvrExecuteQ	ECMA-194
40	ccbsRequest	ECMA-186
41	pathRetain	ECMA-192
42	serviceAvailable	ECMA-192
43	callIntrusionRequest	ECMA-203
44	callIntrusionGetCIPL	ECMA-203
45	callIntrusionIsolate	ECMA-203
46	callIntrusionForcedRelease	ECMA-203
47	callIntrusionWOBRequest	ECMA-203
48	callIntrusionCompleted	ECMA-203
49	cfbOverride	ECMA-192
54	ctmiEnquiry	ECMA-215
55	ctmiDivert	ECMA-215
56	ctmiInform	ECMA-215
57	recallAlert	ECMA-214
58	recallAnswered	ECMA-214
59	chargeRequest	ECMA-212
60	getFinalCharge	ECMA-212
61	aocFinal	ECMA-212
62	aocInterim	ECMA-212
63	aocRate	ECMA-212
64	aocComplete	ECMA-212
65	aocDivChargeReq	ECMA-212
66	cintLeginformation1	ECMA-221
67	cintLegInformation2	ECMA-221
68	cintCondition	ECMA-221
69	cintDisable	ECMA-221
70	cintEnable	ECMA-221
80	mWIActivate	ECMA-242
81	mWIDeactivate	ECMA-242
82	mWIInterrogate	ECMA-242
84	cmnRequest	ECMA-251
85	cmnInform	ECMA-251
86	pathReplaceInvite	ECMA-176

List of ISDN standards

• ETS 300 052 - Multiple Subscriber Number
• ETS 300 055 - Call Waiting
• ETS 300 092 - Calling Line Identification Presentation (CLIP)
• ETS 300 093 - Calling Line Identification Restriction (CLIR)
• ETS 300 097 - Connected Line Identification Presentation (COLP)
• ETS 300 098 - Connected Line Identification Restriction (COLR)
• ETS 300 130 - Malicious Call Identification
• ETS 300 141 - Call Hold
• ETS 300 172 - Circuit-Mode Basic Service
• ETS 300 173 - Called/Calling Line ID Presentation
• ETS 300 182 - Advice Of Charge
• ETS 300 188 - Three Way Conference
• ETS 300 207 - Call Diversion
• ETS 300 237 - Called/Calling Name Presentation
• ETS 300 238 - Called/Calling Name Presentation
• ETS 300 239 - Generic Functional Protocol
• ETS 300 256 - CFU Supplementary Service
• ETS 300 258 - Path Replacement (ANF-PR)
• ETS 300 359 - Call Completion To Busy Subscriber (CCBS)
• ETS 300 260 - Call Transfer By Join (SS-CT)
• ETS 300 261 - Call Transfer - (SS-CT)
• ETS 300 369 - Explicit Call Transfer
• ETS 300 745 - Message Waiting Indication (MWI)
• ETS 300 259 - Path Replacement Additional Network Feature (ANF-PR)
• ETS 301 258 - Recall Supplementary Service (SS-RE)
• ETS 301 919 - Single Step Call Transfer Supplementary Service (SS-SSCT)

Source : European Telecommunications Standards Institute (ETSI)

• CCITT G.703 - Standard for transmitting Voice over digital carriers such as E1 or T1. This provides the specifications for pulse code modulation "PCM" at data rates from 64 kbit/s to 2.048 Mbit/s