SAILOR TT-3084A Fleet 77 SAILOR TT-3086A Fleet 55 - Polaris-as.dk

Chapter 2: Introduction
Service explanation 2.1.3
The low speed services have a lower tariff than the high speed services,
because the high speed services are high quality audio or high speed data
services that require more bandwidth.
• The 128 kbit/s UDI (Unrestricted Digital Information) service enables 2 x 64
kbit/s or 2 x 56 kbit/s bidirectional transmission of data to and from
terrestrial ISDN networks
• The 64 kbit/s UDI (Unrestricted Digital Information) service enables the
bidirectional transmission of data to and from terrestrial 64 kbit/s ISDN
networks. The 56 kbit/s UDI service is similarly used to make a connection
to 56 kbit/s ISDN networks, which are primarily used in North America.
• The Speech and 3.1 kHz audio services make it possible to establish high
quality analogue connections of a quality equal to terrestrial analogue
connections via digital networks/switches. The Speech service is used for
high quality voice connections, whereas 3.1 kHz audio can be used to
transfer analogue signals between fax machines and modems with an
analogue 2-wire interface. The 3.1 kHz audio service is transparent, and is
suitable for all analogue applications including secure telephones.
• The MPDS service is a packet data service where the tariff depends on the
amount of data sent and received. This service is a more cost-effective
solution for web browsing, and other applications where there is no need
for constant transmission of data in both directions. It is also suitable for
applications where a constant connection is required, because the user is
no longer charged the “per minute rate”.
• The Mini-M voice service is only for voice transmission. The voice
transmitted over the satellite is subject to a compression process that
reduces the bandwidth to 4.8 kbit/s and consequently reduces the cost.
• The 9.6 kbit Fax allows you to send and receive fax messages using a
standard office fax machine. This service replaces the previous Mini-M fax
service. Using this service is usually more cost effective compared to the
3.1 kHz audio service.
6 The Inmarsat Fleet Service