Global Title
Encyclopedia
A Global Title is an address
used in the SCCP protocol for routing signaling messages on telecommunications networks. In theory, a global title is a unique address which refers to only one destination, though in practice destinations can change over time.
. In design, however, global titles are quite different. The structure is usually hierarchical, the value can be of variable length, and is not necessarily a wholly numeric value—though it often is for issues of backwards compatibility and association with regular telephone number
s.
applications is officially defined in ITU-T Recommendation Q.713, and further extended in the supporting numbering plan standards. Other national variants of Signalling Connection Control Part (SCCP), such as the American National Standards Institute
variant specified in ANSI T1.112/2000, define their own format for the Global Title. The value of a global title is a sequence of attributes which modify the address value. To summarize:
(regular telephone) numbers for example, indicates the scope
of the address value, such as whether it is an international number (i.e. including the country code), a "national" or domestic number (i.e. without country code), and other formats such as "local" format (e.g. in the U.S., without an area code).
n mobile networks, different translation types are used for analysis of the IMSI and for messages between telephone systems. This parameter is valuable in complex routing problems, where the same number has to be routed differently depending on the circumstances, such as those introduced by number portability
resolution.
routing. Translation examines the destination address (e.g. the number being called) and decides how to identify it over the telephone network. This process can include global title analysis, which is the act of looking up the number and finding a result address, and global title modification.
It is possible for the result of Global Title Translation to be Route on SSN
. This means that, instead of the Global Title routing, lower level MTP
routing will be used for this message from this point on. Equivalently, in a system using SS7 over IP (for example, SIGTRAN
), the result from Global Title Translation may be to a route to an IP server, though the exact details depend greatly on which variant of SS7 over IP is being used.
The variable length of the global title makes certain optimisations that can be used in IP routing are not so easy to use here. The number analysis of a Global Title is most often done in a tree structure. This allows reasonably efficient analysis to any depth which is chosen.
In the end, global title analysis gives some result. The exact possibilities vary from system to system, is sometimes called an "action" or is integrated into the analysis table.
The destination would typically be given as a signalling point code
in an MTP
network, but could also be an IP system if we are using SS7 over IP
and E.214
(although E.212 is also common in America). These simply look like telephone numbers. That is to say, in the most common, international, variant there is a country code
at the start of the number and a Network Code immediately following the country code. Beyond that is the subscriber number or mobile subscriber identity number, though even that may be divided into sections. This structure allows for the use of hierarchical routing.
In America, the limitations of the North American Number Plan mean that the destination country is not immediately obvious from the called party address. However, the fact that there is unified administration means that this can be overcome by having complete analysis at every point where it is needed.
is always used.
At the boundary incoming toward America (this can mean the Signaling Transfer Point at the edge of the American operator's network), numbers routed from European networks are converted from E.214 numbers into E.212 numbers. In the outgoing direction, from America toward the rest of the world, are converted from E.212 numbers into E.214 numbers.
, or in this case, the AUC).
Unfortunately, at the time the subscriber first arrives, we don't know which HLR is the subscriber's HLR. For this reason, the queries have to be routed on the subscriber's identity (IMSI) is used to generate the called party address in the message. How this is done depends whether we are in world area 1 (North America) or somewhere else.
Mainly there are three type of GT in use in mobile networks known as E.164 (MSISDN), E.212(IMSI) and E.214(MGT).
number. See the entry about the IMSI for more details. The E.214 number has a structure which is similar to the E.164 number, and, except in a mobile network it can be routed identically. This means that the same routing tables can be used for both and means considerably reduced administrative overhead in maintaining the tables.
Once a signalling message with an E.214 number enters a mobile network in its own country, the routing is dependent on the operator of that mobile network. In networks without number portability
, it is normal that the MSIN has a structure and that, by analysing the first few digits we can further route the message to the right element.
SCCP is in use. In this case, due to North American standards, the routing of mobility related messages must be done with the E.212 number directly. This has the advantage that in it is easier to identify to which country messages should be routed based on the mobile country code. The design of the North American Number Plan means that there is not a separate country code for each country in North America
. Working with E.214 numbers would not be an insurmountable challenge, as can be seen from the fact that routing of phone calls using E.164 numbers is normal, but it would mean adding full E.164 routing tables to signalling transfer points
where it has never been needed before.
That is the simplest way to search the destination.
based global title. This conversion is reasonably simple, well defined and fully reversible. The conversion is not totally simple since each individual network must be listed.
Recommendation E.214 has been interpreted as suggesting that the analysis of the Mobile Country Code (MCC) and Mobile Network Code (MNC) should be done separately. The relationship between the MNC and the Network Code (NC), however, varies from country to country as does the length of the MNC (two or three digits). This means that the analysis of the MNC is dependent on the analysis of the MCC, or alternatively that the analysis must be done for all five or six digits at once (which is how it is done in practise across at least five separate switch vendors).
Examples
Outbound from America:
Please note the truncation of the number by one digit since E.214 numbers, as with E.164 numbers, have a maximum length of 15 digits.
Inbound toward America:
Network Layer
The network layer is layer 3 of the seven-layer OSI model of computer networking.The network layer is responsible for packet forwarding including routing through intermediate routers, whereas the data link layer is responsible for media access control, flow control and error checking.The network...
used in the SCCP protocol for routing signaling messages on telecommunications networks. In theory, a global title is a unique address which refers to only one destination, though in practice destinations can change over time.
Overview
The Global Title is similar in purpose on the PSTN to the host name on the internetInternet
The Internet is a global system of interconnected computer networks that use the standard Internet protocol suite to serve billions of users worldwide...
. In design, however, global titles are quite different. The structure is usually hierarchical, the value can be of variable length, and is not necessarily a wholly numeric value—though it often is for issues of backwards compatibility and association with regular telephone number
Telephone number
A telephone number or phone number is a sequence of digits used to call from one telephone line to another in a public switched telephone network. When telephone numbers were invented, they were short — as few as one, two or three digits — and were given orally to a switchboard operator...
s.
Structure of the global title value
The structure of a global title for ITU-TITU-T
The ITU Telecommunication Standardization Sector is one of the three sectors of the International Telecommunication Union ; it coordinates standards for telecommunications....
applications is officially defined in ITU-T Recommendation Q.713, and further extended in the supporting numbering plan standards. Other national variants of Signalling Connection Control Part (SCCP), such as the American National Standards Institute
American National Standards Institute
The American National Standards Institute is a private non-profit organization that oversees the development of voluntary consensus standards for products, services, processes, systems, and personnel in the United States. The organization also coordinates U.S. standards with international...
variant specified in ANSI T1.112/2000, define their own format for the Global Title. The value of a global title is a sequence of attributes which modify the address value. To summarize:
Global Title Format
A global title can be in a variety of formats, most of which are each defined in separate standards. The format parameter indicates which of the available formats are in use. Each format can include any of the subsequent parameters.Numbering Plan Indicator
The Numbering Plan Indicator (NPI) describes which numbering plan will be used for the global title. The numbering plan chosen will aid the routing system in determining the correct network system to direct the message.Type of Number
The Type of Number (TON) or Nature of Address Indicator (NAI) parameter, which is of relevance to E.164E.164
E.164 is an ITU-T recommendation that defines the international public telecommunication numbering plan used in the PSTN and some other data networks. It also defines the format of telephone numbers. E.164 numbers can have a maximum of fifteen digits and are usually written with a + prefix...
(regular telephone) numbers for example, indicates the scope
Scope
The word scope may refer to many different devices or viewing instruments, constructed for many different purposes. It may refer to a telescopic sight, an optical device commonly used on firearms. Other uses of scope or Scopes may refer to:...
of the address value, such as whether it is an international number (i.e. including the country code), a "national" or domestic number (i.e. without country code), and other formats such as "local" format (e.g. in the U.S., without an area code).
Translation Type
The translation type (TT) parameter is used in a network to indicate the preferred method of global title analysis (see below). Normally in European networks, this parameter is set to 0 (the default) value. In North AmericaNorth America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
n mobile networks, different translation types are used for analysis of the IMSI and for messages between telephone systems. This parameter is valuable in complex routing problems, where the same number has to be routed differently depending on the circumstances, such as those introduced by number portability
Telephone number portability
Telephone number portability can refer to:*Mobile number portability - telephone number portability for mobile phone users*Local number portability - telephone number portability for land-line users...
resolution.
Global title translation
Global title translation is the SS7 equivalent to IPInternet Protocol
The Internet Protocol is the principal communications protocol used for relaying datagrams across an internetwork using the Internet Protocol Suite...
routing. Translation examines the destination address (e.g. the number being called) and decides how to identify it over the telephone network. This process can include global title analysis, which is the act of looking up the number and finding a result address, and global title modification.
It is possible for the result of Global Title Translation to be Route on SSN
Subsystem number
Signalling Connection Control Part subsystem numbers are used to identify applications within network entities which use SCCP signalling.- GSM and UMTS SSNs :...
. This means that, instead of the Global Title routing, lower level MTP
Message Transfer Part
The Message Transfer Part is part of the Signaling System 7 used for communication in Public Switched Telephone Networks. MTP is responsible for reliable, unduplicated and in-sequence transport of SS7 messages between communication partners....
routing will be used for this message from this point on. Equivalently, in a system using SS7 over IP (for example, SIGTRAN
SIGTRAN
SIGTRAN is the name, derived from signaling transport, of the former Internet Engineering Task Force working group that produced specifications for a family of protocols that provide reliable datagram service and user layer adaptations for Signaling System 7 and ISDN communications protocols....
), the result from Global Title Translation may be to a route to an IP server, though the exact details depend greatly on which variant of SS7 over IP is being used.
Global Title Analysis
Global Title Analysis together with Global Title Translation. The situation in this case is somewhat complicated by the additional parameters possible in the global title. Each set of parameter values (TT=0 NP=E.164, TON=INT) can be treated separately from each other one (TT=0 NP=E.214, TON=INT). This means that, instead of one single table, we potentially need a separate table for each possible set of values.The variable length of the global title makes certain optimisations that can be used in IP routing are not so easy to use here. The number analysis of a Global Title is most often done in a tree structure. This allows reasonably efficient analysis to any depth which is chosen.
In the end, global title analysis gives some result. The exact possibilities vary from system to system, is sometimes called an "action" or is integrated into the analysis table.
The destination would typically be given as a signalling point code
Point Code
An SS7 point code is similar to an IP address in an IP network. It is a unique address for a node , used in MTP layer 3 to identify the destination of a message signal unit ....
in an MTP
Message Transfer Part
The Message Transfer Part is part of the Signaling System 7 used for communication in Public Switched Telephone Networks. MTP is responsible for reliable, unduplicated and in-sequence transport of SS7 messages between communication partners....
network, but could also be an IP system if we are using SS7 over IP
Routing Structure
The most commonly used numbering plans for global title routing are E.164E.164
E.164 is an ITU-T recommendation that defines the international public telecommunication numbering plan used in the PSTN and some other data networks. It also defines the format of telephone numbers. E.164 numbers can have a maximum of fifteen digits and are usually written with a + prefix...
and E.214
E.214
E.214 is a numbering plan used for delivering mobility management related messages in GSM networks. The E.214 number is derived from the IMSI E.212 numbers are composed of two parts. The first, the E.164 part, is made up of a country code followed by the network code. The second part of the...
(although E.212 is also common in America). These simply look like telephone numbers. That is to say, in the most common, international, variant there is a country code
Country code
Country codes are short alphabetic or numeric geographical codes developed to represent countries and dependent areas, for use in data processing and communications. Several different systems have been developed to do this. The best known of these is ISO 3166-1...
at the start of the number and a Network Code immediately following the country code. Beyond that is the subscriber number or mobile subscriber identity number, though even that may be divided into sections. This structure allows for the use of hierarchical routing.
- international SCCP gateways know which systems handle each of the other countries
- the international SCCP gateway belonging to each country knows which SCCP gateways handle each network
- the SCCP gateway of each network knows the networks own internal structure
In America, the limitations of the North American Number Plan mean that the destination country is not immediately obvious from the called party address. However, the fact that there is unified administration means that this can be overcome by having complete analysis at every point where it is needed.
Global Title Modification
In Global Title Translation it is quite normal that at some point the Global Title will have to be changed. This happens, for example, as GSM mobility management messages enter and leave networks in America. In America, typically most routing of mobility management messages for all mobile networks is done using the E.212 (IMSI) number. In international networks, E.214E.214
E.214 is a numbering plan used for delivering mobility management related messages in GSM networks. The E.214 number is derived from the IMSI E.212 numbers are composed of two parts. The first, the E.164 part, is made up of a country code followed by the network code. The second part of the...
is always used.
At the boundary incoming toward America (this can mean the Signaling Transfer Point at the edge of the American operator's network), numbers routed from European networks are converted from E.214 numbers into E.212 numbers. In the outgoing direction, from America toward the rest of the world, are converted from E.212 numbers into E.214 numbers.
Global Title Routing in Mobile Networks
In mobile networks, there are database queries such as "how can I tell if this subscriber is really who he says he is" (MAP_Send_Authentication_Info) which have to be routed back to the database which holds the subscriber's information (the HLRNetwork Switching Subsystem
Network switching subsystem is the component of a GSM system that carries out call switching and mobility management functions for mobile phones roaming on the network of base stations...
, or in this case, the AUC).
Unfortunately, at the time the subscriber first arrives, we don't know which HLR is the subscriber's HLR. For this reason, the queries have to be routed on the subscriber's identity (IMSI) is used to generate the called party address in the message. How this is done depends whether we are in world area 1 (North America) or somewhere else.
Mainly there are three type of GT in use in mobile networks known as E.164 (MSISDN), E.212(IMSI) and E.214(MGT).
- E.164(MSISDN) = CC+NDC+SN, e.g. 91-98-71405178
- E.212(IMSI) = MCC+MNC+MSIN, e.g. 404-68-6600620186 (MTNL delhi)
- E.214(MGT) = combination of E.212 and E.164 (Exact combination is defined in the operators IR21 document)
Mobile Global Title Routing (Except North America)
Everywhere in the world, except North America, the subscriber's IMSI is converted to a Mobile Global Title (MGT) E.214E.214
E.214 is a numbering plan used for delivering mobility management related messages in GSM networks. The E.214 number is derived from the IMSI E.212 numbers are composed of two parts. The first, the E.164 part, is made up of a country code followed by the network code. The second part of the...
number. See the entry about the IMSI for more details. The E.214 number has a structure which is similar to the E.164 number, and, except in a mobile network it can be routed identically. This means that the same routing tables can be used for both and means considerably reduced administrative overhead in maintaining the tables.
Once a signalling message with an E.214 number enters a mobile network in its own country, the routing is dependent on the operator of that mobile network. In networks without number portability
Mobile number portability
Mobile number portability enables mobile telephone users to retain their mobile telephone numbers when changing from one mobile network operator to another.- General overview :MNP is implemented in different ways across the globe...
, it is normal that the MSIN has a structure and that, by analysing the first few digits we can further route the message to the right element.
IMSI Routing (North America)
In World Area 1 (corresponding to North America) ANSIAmerican National Standards Institute
The American National Standards Institute is a private non-profit organization that oversees the development of voluntary consensus standards for products, services, processes, systems, and personnel in the United States. The organization also coordinates U.S. standards with international...
SCCP is in use. In this case, due to North American standards, the routing of mobility related messages must be done with the E.212 number directly. This has the advantage that in it is easier to identify to which country messages should be routed based on the mobile country code. The design of the North American Number Plan means that there is not a separate country code for each country in North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
. Working with E.214 numbers would not be an insurmountable challenge, as can be seen from the fact that routing of phone calls using E.164 numbers is normal, but it would mean adding full E.164 routing tables to signalling transfer points
Signal Transfer Point
A Signal Transfer Point is a router that relays SS7 messages between signaling end-points and other signaling transfer points . Typical SEPs include service switching points and service control points . The STP is connected to adjacent SEPs and STPs via signaling links...
where it has never been needed before.
That is the simplest way to search the destination.
Routing of mobility messages on the ANSI / ITU Boundary
Where a signalling message travels from North America to the rest of the world or from the rest of the world to North America, there must be a conversion done from E.212 based global title to E.214E.214
E.214 is a numbering plan used for delivering mobility management related messages in GSM networks. The E.214 number is derived from the IMSI E.212 numbers are composed of two parts. The first, the E.164 part, is made up of a country code followed by the network code. The second part of the...
based global title. This conversion is reasonably simple, well defined and fully reversible. The conversion is not totally simple since each individual network must be listed.
Recommendation E.214 has been interpreted as suggesting that the analysis of the Mobile Country Code (MCC) and Mobile Network Code (MNC) should be done separately. The relationship between the MNC and the Network Code (NC), however, varies from country to country as does the length of the MNC (two or three digits). This means that the analysis of the MNC is dependent on the analysis of the MCC, or alternatively that the analysis must be done for all five or six digits at once (which is how it is done in practise across at least five separate switch vendors).
Examples
Outbound from America:
- NPI=E.212: 28405 xxxxxxxxxx (284 = BulgariaBulgariaBulgaria , officially the Republic of Bulgaria , is a parliamentary democracy within a unitary constitutional republic in Southeast Europe. The country borders Romania to the north, Serbia and Macedonia to the west, Greece and Turkey to the south, as well as the Black Sea to the east...
MCC + 05 = GlobulGloBulGLOBUL is the second-largest Bulgarian GSM/UMTS operator. The company was founded in 2001 and is 100% owned by Greek telecommunications corporation Cosmote, which is active in four Balkan countries: Greece, Bulgaria, Romania, and Albania...
MNC) -> - NPI=E.214: 359888 xxxxxxxxx (359 = BulgariaBulgariaBulgaria , officially the Republic of Bulgaria , is a parliamentary democracy within a unitary constitutional republic in Southeast Europe. The country borders Romania to the north, Serbia and Macedonia to the west, Greece and Turkey to the south, as well as the Black Sea to the east...
country codeCountry codeCountry codes are short alphabetic or numeric geographical codes developed to represent countries and dependent areas, for use in data processing and communications. Several different systems have been developed to do this. The best known of these is ISO 3166-1...
)
Please note the truncation of the number by one digit since E.214 numbers, as with E.164 numbers, have a maximum length of 15 digits.
Inbound toward America:
- NPI=E.214: 14054 xxxxxxxxx (1 = U.S.United StatesThe United States of America is a federal constitutional republic comprising fifty states and a federal district...
country codeCountry codeCountry codes are short alphabetic or numeric geographical codes developed to represent countries and dependent areas, for use in data processing and communications. Several different systems have been developed to do this. The best known of these is ISO 3166-1...
) -> - NPI=E.212: 310150 xxxxxxxxx (310 = U.S.United StatesThe United States of America is a federal constitutional republic comprising fifty states and a federal district...
MCC + 150 = Cingular MNC)