Solution proposal for the TLDN conflict in the international call delivery IFAST-14 Lima, Perú October 4-5, 2000

The TLDN conflict n n 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 City (current status) Chicago MIN: The Chicago switch sends a ROUTREQ ( ) 4.- The Mexico switch returns a routreq (TLDN = ) 3.- The Mexico switch allocates a 10 digit TLDN in the range  Switch Mexico Switch Chicago 1. A Chicago user calls the roamer 5.- The Chicago switch adds the international prefix to deliver the call because the TLDN begins with 52X PSTN 6.- The Chicago switch makes the international call The PSTN delivers the call to the Mexico switch

Ex. 2: A Chicago user roams to Mexico City (assume a new NPA 525 assigned in New York) Chicago MIN: The Chicago switch sends a ROUTREQ ( ) 4.- The Mexico switch returns a routreq (TLDN = ) 3.- The Mexico switch allocates a 10 digit TLDN in the range  Switch Mexico Switch Chicago 1. A Chicago user calls the roamer 5.- The Chicago switch does not know if the TLDN is from Mexico or New York and can fail the call delivery Switch New York 6.- The Chicago switch makes the call: PSTN 7.- The PSTN delivers th call to thewrong destiny in New York

Ex. 3: A Chicago user roams to Mexico City (Mexico increases the natl. number from 8 to 10 digits) Chicago MIN: The Chicago switch sends a ROUTREQ ( ) 4.- The Mexico switch can return a routreq (TLDN = ) 3.- The Mexico switch allocates a 10 digit TLDN in the range  Switch Mexico Switch Chicago 1. A Chicago user calls the roamer 5.- The Chicago switch does not know if the TLDN is from Mexico or a North America city with NPA 555 Switch USA 6.- The Chicago switch makes the call: PSTN 7.- The PSTN delivers th call to the wrong destiny in a North America city with NPA 555

Alternative #1 to handle the TLDN conflict n n 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. n n 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 and translation tables are used to deliver the call Chicago MIN: The Chicago switch sends a ROUTREQ ( ) 4.- The Mexico switch returns a routreq (TLDN = ) 3.- The Mexico switch sends the IRM of one actual TLDN, say Switch Mexico Switch Chicago 5.- The Chicago switch analyzes the first 6 digits of the TLDN and determines through tables that this number is from Mexico City and have to be routed to the actual DN in Mexico City: PSTN 6.- The Chicago switch makes the international call The PSTN delivers the call to the Mexico switch 1. A Chicago user calls the roamer

Alternative #2 to solve the TLDN conflict n n 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. n n 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: The Chicago switch sends a ROUTREQ ( ) 4.- The Mexico switch returns routreq (digits destination= , nature of number=international ) 3.- The Mexico switch sends a 12 digits TLDN in the range  Switch Mexico Switch Chicago PSTN 6.- The Chicago switch makes the international call The PSTN delivers the call to the Mexico switch 1. A Chicago user calls the roamer Alternative #2: A Chicago user roams to Mexico City and the proper parameters of IS-41C are used 5.- The Chicago switch identifies the international nature of the number and can handle the 12 digits lenght of the TLDN

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

Conclusions (cont.) n n 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. n n 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.