System information

34 221 02-FGB 101 544 Uen A - September 2008
7 Fax Service (W35 only)
To enable Fax support over the WCDMA network, Ericsson W35 uses SIP
(Session Initiation Protocol).
The Ericsson W35 acts as a media gateway between the POTS interface
and the IP network and uses the T.38 protocol. To enable a fax call a SIP
server and PSTN gateway is required. The SIP server needs to support SIP
according to RFC 3261 and the media gateway needs to support SIP and
T.38.
The Ericsson W35 supports G3 fax as specified in ITU-T T.30 Annex A.
Older standards, as G1 and G2, and the newer superG3 (sometimes called
V.34fax) are not supported.
7.1 IMS User Agent
The IMS (SIP) User Agent is associated to the “Phone/Fax” port on the
Ericsson W35. This integrated User Agent controls VoIP sessions and
manages and controls the media streams by using the SIP protocol
towards the SIP Server and Media Gateway.
7.2 IMS Call Server
The IMS User Agent requires access to one or more IMS Call servers (also
called SIP proxy/servers). A list can be created with configuration details for
different SIP server/proxy settings and possibly an outbound proxy.
7.3 Media Codec
The Ericsson W35 supports the following CODECs:
• G.711a-law (used for VoIP)
• G.711u-law (used for VoIP)
• T.38 (used for Fax services).
7.3.1 G.711a-law / GG.711 u-law
The G.711a-law and G.711u-law CODECs are used for VoIP and the
settings include Voice Activity Detection (VAD); enable/disable silence
suppression, and the RTP payload size.
7.3.2 T.38
The T.38 settings are used for Fax and even if the parameter name says
T.38 most of the items are basically T.30 settings.
Depending on radio network characteristics there might be a need for fine
tuning the T.38 parameters.