Solution proposal for the TLDN conflict in the international call delivery

IFAST-14

Lima, Perú

October 4-5, 2000

The TLDN conflictThe TLDN conflict

The TLDN conflict appears in the international call delivery scenario when there is an exchange of a 10 digit temporal local directory number (TLDN) between two countries with different numbering plans.

Ex. 1: A Chicago user roams to Mexico CityEx. 1: A Chicago user roams to Mexico City(current status)(current status)

Chicago MIN:312-224-1234

2.- The Chicago switch sends a ROUTREQ (312-224-1234)

4.- The Mexico switch returns aroutreq (TLDN = 52-5101-5212)

3.- The Mexico switchallocates a 10 digitTLDN in the range52-5101-520052-5101-5299

SwitchMexico

SwitchChicago

1. A Chicago usercalls the roamer

5.- The Chicago switchadds the internationalprefix to deliver the callbecause the TLDN beginswith 52X

PSTN

6.- The Chicago switchmakes the international call011-52-5101-5212

7.- The PSTN deliversthe call to the Mexico switch

Ex. 2: A Chicago user roams to Mexico CityEx. 2: A Chicago user roams to Mexico City(assume a new NPA 525 assigned in New York)(assume a new NPA 525 assigned in New York)

Chicago MIN:312-224-1234

2.- The Chicago switch sends a ROUTREQ (312-224-1234)

4.- The Mexico switch returns aroutreq (TLDN = 52-5101-5212)

3.- The Mexico switchallocates a 10 digitTLDN in the range52-5101-520052-5101-5299

SwitchMexico

SwitchChicago

1. A Chicago usercalls the roamer

5.- The Chicago switch doesnot know if the TLDN is fromMexico or New York and canfail the call delivery

SwitchNew York

6.- The Chicago switch makesthe call: 1-525-101-5212

PSTN

7.- The PSTN delivers th callto thewrong destiny 525-101-5212in New York

Ex. 3: A Chicago user roams to Mexico CityEx. 3: A Chicago user roams to Mexico City(Mexico increases the natl. number from 8 to 10 digits)(Mexico increases the natl. number from 8 to 10 digits)

Chicago MIN:312-224-1234

2.- The Chicago switch sends a ROUTREQ (312-224-1234)

4.- The Mexico switch can return aroutreq (TLDN = 55-5101-5212)

3.- The Mexico switchallocates a 10 digitTLDN in the range52-55-5101-520052-55-5101-5299

SwitchMexico

SwitchChicago

1. A Chicago usercalls the roamer

5.- The Chicago switch doesnot know if the TLDN is fromMexico or a North Americacity with NPA 555

SwitchUSA

6.- The Chicago switch makesthe call: 1-555-101-5212

PSTN

7.- The PSTN delivers th callto the wrong destiny 555-101-5212in a North America city with NPA 555

Alternative #1 to handle the TLDN conflictAlternative #1 to handle the TLDN conflict

The visited switch could send the IRM in the TLDN field and the home switch would have to translate the IRM to a real directory number of the country that sends the TLDN.

The drawback of this alternative is that the switch would have to store translation tables of IRM’s of all the countries with roaming agreements.

Alternative #1: A Chicago user roams to Mexico City Alternative #1: A Chicago user roams to Mexico City and translation tables are used to deliver the calland translation tables are used to deliver the call

Chicago MIN:312-224-1234

2.- The Chicago switch sends a ROUTREQ (312-224-1234)

4.- The Mexico switch returns aroutreq (TLDN = 059501-5212)

3.- The Mexico switchsends the IRM of oneactual TLDN, say52-55-5101-5212

SwitchMexico

SwitchChicago

5.- The Chicago switchanalyzes the first 6 digits ofthe TLDN and determinesthrough tables that this numberis from Mexico City and haveto be routed to the actualDN in Mexico City:52-55-5101-5212

PSTN

6.- The Chicago switchmakes the international call011-52-55-5101-5212

7.- The PSTN deliversthe call to the Mexico switch1. A Chicago user

calls the roamer

Alternative #2 to solve the TLDN conflictAlternative #2 to solve the TLDN conflict

The switches would have to handle the international option in the field “nature of the number” of the parameter “digits” of IS-41C to determine if a TLDN is coming from another country.

Additionally, to manageTLDN’s of lengh different from 10, the parameter “digits” of IS-41C has to be activated to variable lenght up to 15 digits, as allowed in IS-41C.

Chicago MIN:312-224-1234

2.- The Chicago switch sends a ROUTREQ (312-224-1234)

4.- The Mexico switch returns routreq(digits destination=52-55-5101-5212,nature of number=international)

3.- The Mexico switchsends a 12 digits TLDNin the range52-55-5101-520052-55-5101-5299

SwitchMexico

SwitchChicago

PSTN

6.- The Chicago switchmakes the international call011-52-55-5101-5212

7.- The PSTN deliversthe call to the Mexico switch1. A Chicago user

calls the roamer

Alternative #2: A Chicago user roams to Mexico City Alternative #2: A Chicago user roams to Mexico City and the proper parameters of IS-41C are usedand the proper parameters of IS-41C are used

5.- The Chicago switchidentifies the internationalnature of the number and canhandle the 12 digits lenght ofthe TLDN

ConclusionsConclusions

The TLDN conflict has been avoided through provisional solutions but in general, these schemes do not work because the differences in the numbering plan of the countries.

The TLDN conflict is specially relevant in those countries with national numbers of length different of 10 digits.

Conclusions (cont.)Conclusions (cont.)

The first alternative proposed to handle the conflict is to use translation tables to relate IRM’s to TLDN’s. However, this alternative can be complex to implement.

The second alternative is activating the proper fields of IS-41C in the mobile systems to accept international and variable length TLDN’s. This is the best solution but implies a certain cost and a strong cooperation of industry to implement this solution internationally.