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1 Introduction
This document gives a brief description of the Fax over IP implementation
in the Ericsson W25.
1.1 Background
The Ericsson W25 is intended for residential and SOHO. The focus for the
Ericsson W25 is to enable both broadband data and voice calls.
Additionally support for analog Fax operation is essential when targeting
business users such as SOHO users.
Fax support in GSM mobile networks is standardized, but not in 3G mobile
networks. The only options available in 3G mobile networks are T.37, store
and forward mailbox, or T.38 Fax over IP. Seeing that Fax communication
is considered legally binding when doing business, the demand on Fax
operation is that the sender of a Fax can get a receipt that the fax has been
delivered to the recipient in real-time. Therefore Ericsson has chosen Fax
over IP (T.38) using packet switched connection in the Ericsson W25 to
enable Fax operation in 3G mobile networks as this is the only option that
can guarantee that a fax has been delivered to the recipient in real-time.
This can be done thanks to HS(D)PA introduced in 3G mobile networks
with features such as increased data bandwidth and reduced delay.
