Cisco SPA301 Administration Manual page 154

Configuring Security, Quality, and Network Features
Configuring Voice Codecs
Cisco Small Business SPA300 Series, SPA500 Series, and WIP310 IP Phone Administration Guide
Parameter
DTMF Tx Volume
for AVT Packet
Use Remote Pref
Codec
Codec Negotiation
Description
Allows you to manually configure the AVT Tx volume. The
value of this parameter is inserted into the volume field of
the payload in the AVT packet.
Values are based on the AVT specification as described in
RFC-2833, RTP Payload for DTMF Digits, Telephony Tones
and Telephony Signals
volume field is represented by 6 bits, and describes the
power level of the tone, expressed in dBm0 after dropping
the sign.
Valid range for this parameter is 0 to 63. If the provisioned
value is negative, it is negated first. Thereafter, if the value
is beyond the high limit of 63, it is clipped to 63.
The default value is 0 and the recommended setting.
However, some gateways do not accept this volume
setting. If the gateway does not accept a value of 0, the
DTMF tone is not relayed to the remote end. As a
workaround for the phone to interoperate with those
gateways, you can change the value to a value greater
than 0.
To set the phone to communicate by using the remote
phone-preferred codec, select yes. If set to no, the Cisco
IP phone communicates by using its own preferred codec
(as indicated in the Preferred Codec field and in the SDP
by order of preferences). The default vale is no.
When set to Default, the Cisco IP phone responds to an
Invite with a 200 OK response advertising the preferred
codec only. When set to List All, the Cisco IP phone
responds listing all the codecs that the phone supports.
The default value is Default.
. According to RFC-2833, the
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