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5 The VoIP System
To enable a fax call a SIP server and Fax gateway is required. There is
actually no need for extra features more than a basic call. Supplementary
services are not required.
PSTN
Fax
Gateway
SIP
Server
Edge
Router
VoIP System
IP
The SIP server needs to support SIP according to RFC 3261 and the Fax
gateway needs to support SIP and T.38. In addition to this the operator
might have requirements on charging etc, which is not taken into account in
this document. There are several products on the market, which fulfills the
basic requirements.
The Ericsson W25 will be tested towards Ericsson’s own VoIP system
called IMT (IMS Multimedia Telephony), which is described below.
5.1 Ericsson IMT
The Ericsson W25 will interoperate with Ericsson IMS solution called IMT
(IMS Multimedia Telephony). It’s not required to have a complete IMT
system to get the Fax over IP to work, so only the mandatory IMT building
blocks are describe in this document. The mandatory blocks consist of a
PSTN gateway and Subsystem Core.
MGC
MGW
PSTN
SIP
server
GGSN
PSTN GATEWAYS
