North American Numbering Council
c/o Columbia Institute for Tele-Information
Columbia Business School
1A Uris Hall
3022 Broadway
New York, NY 10027-6902
July 25, 2005
Mr. Thomas J. Navin 
Chief, Wireline Competition Bureau
Federal Communications Commission
445 Twelfth Street, S.W.
Washington, D.C. 20554
RE:  Request for FCC Endorsement of LNPA N-1 Architecture Recommendation
Dear Mr. Navin:
The purpose of this letter is to urge the Commission to endorse a recommendation made 
by the NANC’s Local Number Portability Administration Working Group (LNPA WG) 
for determining which service provider is responsible for querying number portability 
databases, particularly with respect to Extended Area Service (EAS) calls.  Such an 
endorsement should eliminate or at least substantially mitigate confusion and disputes 
over this responsibility.
The recommendations were made by the LNPA WG in January, partly in response to a 
request from the Bureau’s staff for the NANC’s advice on this matter. Unfortunately, due 
to a clerical error on my part I have not forwarded the recommendations until today.  I 
apologize for the delay.
As background, a carrier involved in establishing a telephone connection must query a 
local number portability database to determine which carrier is responsible for finally 
terminating the call to the ported or pooled telephone number being called.  Typically, the 
carrier before the final terminating carrier (the so-called “N-1 carrier”) is responsible for 
making the database query. As an example, for a local call the originating carrier is also 
the N-1 carrier and is responsible for performing the query in its network or contracting 
with another entity to perform the queries on its behalf.  Similarly, for interLATA toll 
calls the interexchange carrier is the N-1 carrier and is responsible for performing the 
necessary query.
The LNPA WG had been working on extensive guidelines for the overall N-1 
Architecture when the Commission staff specifically requested the NANC to review the 
N-1 process for Extended Area Service (EAS) calls.  The LNPA WG’s full report, which 
is attached for your information, was forwarded to telecommunications service operators 
by the trade associations represented on the NANC.
With respect to EAS, the LNPA WG’s recommendation, included on page 11 of the full 
report, is as follows:
· On intraLATA calls to EAS codes, the originating carrier is the N-1 carrier and is 
responsible for the query on all calls to portable EAS codes.
· In cases where the originating carrier’s switch supports the function to route 
interLATA EAS calls to ported numbers as a local call via an interLATA LRN, 
and trunking to all potential final destinations (or their POIs in the EAS area) 
have been established, the query will be performed in the originating switch.  
· On interLATA calls to EAS codes where the originating carrier does not support 
the function to route the call as a local call to ported numbers via an interLATA 
LRN, the donor carrier in the terminating LATA performs the role of the N-1 
carrier (i.e does the database dip and routes the call to the switch serving the 
ported number).  In this instance, the donor carrier will perform the LNP query in 
the terminating LATA in either that carrier’s donor end office or terminating 
LATA tandem, whichever terminates trunks from the originating LATA on calls to 
EAS codes.  (Note that the terminating LATA tandem case is only applicable if the 
donor carrier has a tandem in the terminating LATA, and all switches in the 
originating LATA that can place local calls to the EAS codes in the terminating 
LATA have trunking to the tandem in the terminating LATA per mutually accepted 
interconnect agreements.)  The originating carrier is responsible for 
compensation to the donor carrier for performing the N-1 database dip function.  
The donor carrier in the terminating LATA may charge the originating carrier for 
transit (consisting of transport and switching) of the call.
This language takes into account current technical limitations and regulatory 
constraints as well as existing configuration issues.  Carriers may consider 
making modifications to their querying and routing arrangements as technology 
upgrades and changes to interconnecting configurations permit.
To minimize problems and disputes with respect to database query responsibilities, I 
recommend, on the NANC’s behalf, that the Commission endorse all of the LNPA WG’s 
recommendations (particularly the EAS proposals) and, as quickly as possible, take any 
other steps that may be necessary to encourage service providers to abide by them.  
Please feel free to contact me if you or members of your staff have any questions.
Sincerely,
/Signed/
Robert C. Atkinson
NANC Chair
Attachment
cc: Regina Brown, FCC
Marilyn Jones, FCC
Lisa Gelb, FCC
Narda Jones, FCC
Cheryl Callahan, FCC
NANC Members