Cisco Systems Linksys PAP2, RT31P2 4.6. Media and SDP (Session Description Protocol) Configuration

Ext SIP Port External port to substitute for the actual SIP port of

the unit in all outgoing SIP messages. If “0” is

specified, no SIP port substitution is performed.

Port 0

Ext RTP Port Min External port mapping of <RTP Port Min>. If this

value is non-zero, the RTP port number in all

outgoing SIP messages is substituted by the

corresponding port value in the external RTP port

range.

Port 0

NAT Mapping Enable Enable the use of externally mapped of IP address

and SIP/RTP ports in SIP messages. The mapping

may be discovered by any of the supported

methods.

Bool No

NAT Keep Alive Enable If set to “yes”, the configured <NAT Keep Alive

Msg> is sent periodically every <NAT Keep Alive

Intvl> seconds.

Bool No

NAT Keep Alive Msg Contents of the keep-alive message to be sent to a

given destination periodically to maintain the

current NAT-mapping. It could be an empty string. If

value is $NOTIFY, a NOTIFY message is sent as

keep alive. If value is $REGISTER, a REGISTER

message w/o Contact is sent.

Str31 $NOTIFY

NAT Keep Alive Dest Destination to send NAT keep alive messages to. If

value is $PROXY, it will be sent to the current proxy

or outbound proxy

FQDN $PROXY

Use Outbound Proxy Enable the use of <Outbound Proxy>. If set to “no”,

<Outbound Proxy> and <Use OB Proxy in Dialog)

is ignored.

Bool No

Outbound Proxy SIP Outbound Proxy Server where all outbound

requests are sent as the first hop. FQDN No

Use OB Proxy In Dialog Whether to force SIP requests to be sent to the

outbound proxy within a dialog. Ignored if <Use

Outbound Proxy> is “no” or <Outbound Proxy> is

empty

Bool Yes

NAT Keep Alive Intvl Interval between sending NAT-mapping keep alive

message in sec Uns16 15

4.6. Media and SDP (Session Description Protocol) Configuration

4.6.1. DTMF and Hookflash

By default, the PHONE ADAPTER sends DTMF to the far end using RFC2833-style "AVT tones".

This method of conveying DTMF tones sends a representation of a tone (someone pressed the "7"

key) to the RTP peer as a separate RTP audio codec, but with timing information synchronized with

the speech audio codec. This method of DTMF conveyance works in most topologies, however in

some environments, the service provider may have an application server which is not in the media

path, or may be responsible for protocol conversion to a protocol or device which does not support

AVT tones.

Likewise, hookflash events by default are handled internally by the PHONE ADAPTER and used to

trigger supplementary services which are implemented on the PHONE ADAPTER. If a provider needs

to convey a hookflash event to an application server to initiate a network-oriented feature, the

PHONE ADAPTER is configurable to send these events.