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Cisco SIP IP Phone Administrator Guide
Chapter 3      Managing Cisco SIP IP Phones
Modifying the Phone’s SIP Settings
Table 3-6 Additional SIP Configuration Parameters
Parameter Required or Optional
Messages URI Optional Number to call to check voice mail. This number is called when the 
Messages key is pressed.
Preferred Codec Optional Codec to use when initiating a call. Valid values are g711alaw, g711ulaw, 
and g729a. The default is g711ulaw.
Out of Band DTMF Optional Whether to detect and generate the out-of-band signaling (for tone 
detection on the IP side of a gateway) and if so, when. The Cisco SIP IP 
phone supports out-of-bound signaling via the AVT tone method. Valid 
values are:
• none—Do not generate DTMF digits out-of-band.
• avt—If requested by the remote side, generate DTMF digits 
out-of-band (and disable in-band DTMF signaling); otherwise, do not 
generate DTMF digits out-of-band.
• avt_always—Always generate DTMF digits out-of-band. This option 
disables in-band DTMF signaling.
The default is avt.
Register with Proxy Optional Whether the phone must register with a proxy server during initialization. 
Valid values are Yes and No. Select the No soft key to disable registration 
during initialization. Select the Yes soft key to enable registration during 
initialization. The default is No. After a phone has initialized and 
registered with a proxy server, changing the value of this parameter to No 
unregisters the phone from the proxy server. To reinitiate a registration, 
change the value of this parameter back to Yes.
Note If you enable registration, and authentication is required, you must 
specify values for the Authentication Name and Authentication 
Password parameters.
Register Expires Optional The amount of time, in seconds, after which a REGISTRATION request 
expires. This value is used the Expire header field. The valid value is any 
positive number; however, Cisco recommends 3600 seconds. The default 
is 3600.
TFTP Directory Required if 
phone-specific 
configuration files are 
located in a 
subdirectory
Path to the TFTP subdirectory in which phone-specific configuration files 
are stored.
Phone Label Optional Label to display on the top status line of the LCD. This field is for 
end-user display only. For example, a phone’s label can display “John 
Doe’s phone.” Up to 11 characters can be used when specifying the phone 
label. 
Enable VAD Optional Specifies whether VAD is enabled or disabled.
VoIP Control Port Optional The UDP port used for SIP messages. Default is 5060. All SIP 
REQUESTS use voip_control_port as the UDP source port when 
nat_enable = 1. Valid values are 1025 to 65535.