User`s guide

VoiceFinder AP200 VoIP Residential Gateway (RGW) User’s Guide Version 1.1
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relay, all gateways and gatekeepers in this network are able to send faxes to
other remote offices or to the offices of another company on the IP network.
[Figure 5-9] IP Network for T.38 Fax Relay
For example, when a fax is sent from the originating gateway, a voice call is
established. The terminating gateway detects the fax tone generated by the
answering fax machine. The VoIP H.323 call stack then starts a T.38 mode
request using H.245 procedures. If the opposite end of the call acknowledges
the T.38 mode request, the initial audio channel is closed and a T.38 fax relay
channel is opened. When the fax transmission is completed, the call reverts to
voice mode.
IP Network
C
ompany A
Office 1
C
ompany B
Office 1
C
ompany B
Office 2
C
ompany A
Office 2
Gatekeepe
r
Alternate
Gatekeeper
Third-party T.38
Gateway
AP200 VoIP
Gateway
AP200 VoIP
Gateway
Gateway