Solution proposal for the TLDN conflict in the international call delivery

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Solution proposal for the TLDN conflict in the
international call delivery

• IFAST-14
• Lima, Perú
• October 4-5, 2000

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The 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.

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Ex. 1 A Chicago user roams to Mexico
City(current status)
Chicago MIN 312-224-1234
5.- The Chicago switch adds the
international prefix to deliver the call because
the TLDN begins with 52X
2.- The Chicago switch sends a ROUTREQ
(312-224-1234)
3.- The Mexico switch allocates a 10 digit TLDN
in the range 52-5101-5200 Û 52-5101-5299
4.- The Mexico switch returns a routreq (TLDN
52-5101-5212)
Switch Mexico
Switch Chicago
6.- The Chicago switch makes the international
call 011-52-5101-5212
7.- The PSTN delivers the call to the Mexico
switch
PSTN
1. A Chicago user calls the roamer
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Ex. 2 A Chicago user roams to Mexico
City(assume a new NPA 525 assigned in New York)
Chicago MIN 312-224-1234
5.- The Chicago switch does not know if the TLDN
is from Mexico or New York and can fail the call
delivery
2.- The Chicago switch sends a ROUTREQ
(312-224-1234)
3.- The Mexico switch allocates a 10 digit TLDN
in the range 52-5101-5200 Û 52-5101-5299
4.- The Mexico switch returns a routreq (TLDN
52-5101-5212)
Switch Mexico
Switch Chicago
6.- The Chicago switch makes the call
1-525-101-5212
PSTN
1. A Chicago user calls the roamer
7.- The PSTN delivers th call to thewrong destiny
525-101-5212 in New York
Switch New York
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Ex. 3 A Chicago user roams to Mexico
City(Mexico increases the natl. number from 8 to
10 digits)
Chicago MIN 312-224-1234
5.- The Chicago switch does not know if the TLDN
is from Mexico or a North America city with NPA
555
2.- The Chicago switch sends a ROUTREQ
(312-224-1234)
3.- The Mexico switch allocates a 10 digit TLDN
in the range 52-55-5101-5200 Û 52-55-5101-5299
4.- The Mexico switch can return a routreq (TLDN
55-5101-5212)
Switch Mexico
Switch Chicago
6.- The Chicago switch makes the call
1-555-101-5212
PSTN
1. A Chicago user calls the roamer
7.- The PSTN delivers th call to the wrong
destiny 555-101-5212 in a North America city with
NPA 555
Switch USA
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Alternative 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
  IRMs of all the countries with roaming
  agreements.

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Alternative 1 A Chicago user roams to Mexico
City and translation tables are used to deliver
the call
Chicago MIN 312-224-1234
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 52-55-5101-5212
2.- The Chicago switch sends a ROUTREQ
(312-224-1234)
3.- The Mexico switch sends the IRM of one actual
TLDN, say 52-55-5101-5212
4.- The Mexico switch returns a routreq (TLDN
059501-5212)
Switch Mexico
Switch Chicago
6.- The Chicago switch makes the international
call 011-52-55-5101-5212
7.- The PSTN delivers the call to the Mexico
switch
PSTN
1. A Chicago user calls the roamer
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Alternative 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 manageTLDNs 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.

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Alternative 2 A Chicago user roams to Mexico
City and the proper parameters of IS-41C are used
Chicago MIN 312-224-1234
5.- The Chicago switch identifies the
international nature of the number and can handle
the 12 digits lenght of the TLDN
2.- The Chicago switch sends a ROUTREQ
(312-224-1234)
3.- The Mexico switch sends a 12 digits TLDN in
the range 52-55-5101-5200 Û 52-55-5101-5299
4.- The Mexico switch returns routreq (digits
destination52-55-5101-5212, nature of
numberinternational)
Switch Mexico
Switch Chicago
6.- The Chicago switch makes the international
call 011-52-55-5101-5212
7.- The PSTN delivers the call to the Mexico
switch
PSTN
1. A Chicago user calls the roamer
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Conclusions

• 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.

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Conclusions (cont.)

• The first alternative proposed to handle the
  conflict is to use translation tables to relate
  IRMs to TLDNs. 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 TLDNs. This is
  the best solution but implies a certain cost and
  a strong cooperation of industry to implement
  this solution internationally.