HUT Comms Lab., Timo O. Korhonen
Present-day PSTN services
nBasic
service
nBearer
service (local loop access): analog (/ISDN)
nValue-added
services (telephonist-originated) services as
ndirectory
inquiry (118)
nweather,
stock exchange, ticket reservation ...
nSupplementary
services (Intelligent Terminal (IN) implementation)
ndistributed
supplementary as ‘call forwarding unconditional’, ‘call waiting’, ‘queuing’
...
ncentralized supplementary services (IN) use specialized routing &
charging as VPN, credit card calls, free phone (receiver pays), universal access
number (connected automatically to the nearest office), ...
Basic
Value
Added
Added
Supplementary