3Com VCX v7111 User Manual page 21

T.38 real time Fax (using SIP).
If the remote side includes the fax maximum rate parameter in the Session
Description Protocol (SDP) body of the INVITE message, the gateway returns the
same rate in the response SDP.
Works with Proxy or without Proxy, using an internal routing table.
Fallback to internal routing table if Proxy is not responding.
Supports up to four Proxy servers. If the primary Proxy fails, the gateway automatically
switches to a redundant Proxy.
Supports domain name resolving using DNS NAPTR and SRV records for Proxy,
Registrar and domain names that appear in the Contact and Record-Route headers.
Supports Load Balancing over Proxy servers using Round Robin or Random Weights.
Proxy or Registrar Registration, such as:
REGISTER sip:servername SIP/2.0
VIA: SIP/2.0/UDP 212.179.22.229;branch=z9hG4bRaC7AU234
From: <sip:GWRegistrationName@sipgatewayname>;tag=1c29347
To: <sip:GWRegistrationName@sipgatewayname>
Call-ID: 10453@212.179.22.229
Seq: 1 REGISTER
Expires: 3600
Contact: sip:GWRegistrationName@212.179.22.229
Content-Length: 0
The servername string is defined according to the following rules:
The servername is equal to RegistrarName if configured. The RegistrarName can be
any string.
Otherwise, the servername is equal to RegistrarIP (either FQDN or numerical IP
address), if configured.
Otherwise the servername is equal to ProxyName if configured. The ProxyName can
be any string.
Otherwise the servername is equal to ProxyIP (either FQDN or numerical IP
address).
The GWRegistrationName parameter can be any string. If the parameter is not defined,
the UserName parameter is used instead.
The sipgatewayname parameter (defined in the ini file or set from the Web browser), can
be any string. Some Proxy servers require that the sipgatewayname (in REGISTER
messages) is set equal to the Registrar / Proxy IP address or to the Registrar / Proxy
domain name.
The REGISTER message is sent to the Registrars IP address (if configured) or to the
Proxy's IP address. The message is sent per gateway or per gateway endpoint
according to the AuthenticationMode parameter. Usually the FXS gateways are
registered per gateway port, while FXO gateways send a single registration message,
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3Com VCX V7111 VoIP Gateway User Guide
21