Ovislink OV804WV User Manual page 199

MWI stands for message waiting indicator. When this is
enabled, DSL router sends a SIP subscribe message to proxy,
asking for a notification when its voice mail status changes.
When its status do changes, proxy sends a notify message to
gateway, causing a MWI tone streamed to user's handset.
Enable T38 support
Checking this box enables T38 support. When doing a fax
transmission on DSL router, after fax tone has been detected,
fax transmission switches to T38 mode.
Registration Expire Timeout
It is the interval, when DSL router initiates a new registration
since last one. It is also known as registration assurance timer.
The gateway uses this mechanism to keep its binding record
updated.
Dial Plan Setting
Set the VoIP dial plan. If user-dialed number matches it, the
number is processed by DSL router immediately.
Dtmf Relay setting
Set DTMF transmitting method, which can be following values:

SIP Info: use SIP info message to transmit DTMF digits.
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