Configuring Security, Quality, and Network Features
Configuring Voice Codecs
Cisco Small Business SPA300 Series, SPA500 Series, and WIP310 IP Phone Administration Guide 154
5
 
DTMF Tx Volume 
for AVT Packet
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
. According to RFC-2833, the 
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.
Use Remote Pref 
Codec
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.
Codec Negotiation 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.
Parameter  Description