NTT disclosed plans to migrate remaining traffic on its PSTN to IP beginning around 2020, complete the process around 2025, and then deactivate the legacy PSTN infrastructure. Some capabilities currently provided by the PSTN will be terminated at that point, hence NTT is providing customers and regulators with advanced notice of its long term plans.
NTT noted that it is already a world leader in optical broadband coverage. Optical broadband services are currently offered to approximately 14 million households and network coverage area is at 90%. The company began providing NGN services in 2008 and will cover nearly all existing optical service areas by the end of March 2011.
Meanwhile, the number of PSTN fixed-line telephone users in Japan is declining annually by approximately 10% as a result of the shift to mobile phones and IP phones. NTT said it is difficult to estimate how many PSTN fixed-line telephone users will remain in the future, but a certain level of such users is expected. Now, the question is how to migrate these users into the optical + IP network, and then deactivate the PSTN infrastructure. Existing PSTN switches will have reached the end of their useful lives by 2025.
Many PSTN services will be fully migrated to IP, including emergency numbers (police (110), marine emergencies (118), fire (119)), time (117), weather reports (177), Directory Assistance (104), telegrams (115), caller ID
display (Number Display), anonymous call rejection, nuisance call blocking, etc. However, NTT said other PSTN services will not the transition. Examples include INS networks, centrex service, “denwaban” answering service, payphones, etc.
Presently, IP phones are still connected through the PSTN, which has many customers, and NTT East and NTT West IP networks are not connected directly with other carrier’s IP networks nor are other carrier’s IP networks interconnected among themselves. In the future, all these interconnections will be IP.
http://www.ntt.co.jphttp://www.ntt-east.co.jp/release_e/1011/pdf/101102a_1.pdf
