Cisco SPA1112 Provisioning Manual page 97

Voice Parameters
<SAS_Inbound_RTP_Sink_1_>
<SAS_Inbound_RTP_Sink_2_>
<NAT_Mapping_Enable_1_> through
<NAT_Mapping_Enable_13_>
<NAT_Keep_Alive_Enable_1_> through
<NAT_Keep_Alive_Enable_13_>
<NAT_Keep_Alive_Msg_1_> through
<NAT_Keep_Alive_Msg_13_>
<NAT_Keep_Alive_Dest_1_> through
<NAT_Keep_Alive_Dest_13_>
Provisioning Guide for Cisco SPA100 and SPA200 Series Analog Telephone Adapters
The purpose of this parameter is to work around devices that
do not play inbound RTP if the SAS line declares itself as a
send-only device and tells the client not to stream out audio.
This parameter is an FQDN or IP address of an RTP sink to be
used by the SAS line in the SDP of its 200 response to
inbound INVITE from a client. It will appear in the c = line and
the port number, if specified, will appear in the m = line of the
SDP. If this value is not specified or is equal to 0, then c =
0.0.0.0 and a=sendonly will be used in the SDP to tell the SAS
client to not to send any RTP to this SAS line. If a non-zero
value is specified, then a=sendrecv and the SAS client will
stream audio to the given address. Special case: If the value is
$IP, then the SAS line's own IP address is used in the c = line
and a=sendrecv. In that case the SAS client will stream RTP
packets to the SAS line.
Default setting: blank
To use externally mapped IP addresses and SIP/RTP ports in
SIP messages, select yes. Otherwise, select no.
Default setting: no
To send the configured NAT keep alive message periodically,
select yes. Otherwise, select no.
Default setting: no
Enter the keep alive message that should be sent periodically
to maintain the current NAT mapping. If the value is $NOTIFY, a
NOTIFY message is sent. If the value is $REGISTER, a
REGISTER message without contact is sent.
Default setting: $NOTIFY
Destination that should receive NAT keep alive messages. If
the value is $PROXY, the messages are sent to the current
proxy server or outbound proxy server.
Default setting: $PROXY
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