Application Guide
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DP750/DP720 Administration Guide 
Version 1.0.3.37 
request to a SIP server. The time it takes between sending out the request to the 
point of getting a response is the SIP T1 timer. If no response is received the timeout 
is increased to (2*T1) and then (4*T1). Request re-transmit retries would continue 
until a maximum amount of time defined by T2.   
Default is 0.5 seconds. 
SIP T2 Timeout 
Identifies  maximum  retransmission  interval for  non-INVITE  requests  and  INVITE 
responses. Retransmitting and doubling of T1 continues until it reaches T2 value. 
Default is 4 seconds. 
SIP Timer D 
Configures SIP timer D defined in RFC3261. Range of values 0-64. Default is 0. 
Remove OBP from 
Route Header 
Removes outbound  proxy information  from “Route”  header when  sending SIP 
packets. Default is No. 
Support SIP   
Instance ID 
Adds  “SIP  Instance  ID”  attribute  to  “Contact”  header  in  REGISTER  request  as 
defined in IETF SIP outbound draft. Default is No. 
Hold Target Before 
Refer 
Sends  re-INVITE  to hold  transfer  target before  sending REFER  message  to 
transferee. Default is Yes. 
Refer-To Use Target 
Contact 
Includes  target’s  “Contact”  header  information  in  “Refer-To”  header  when  using 
attended transfer. Default is No.  
SUBSCRIBE for 
MWI 
Sends  periodic  “SUBSCRIBE”  requests  (depends  on  “Register  Expiration” 
parameter) for message waiting indication service. Default is No. 
Enable 100rel 
Appends “100rel” attribute to the “required” header of the initial signaling messages. 
Default is No. 
TEL URI 
Indicates E.164 number in  “From” header by adding “User=Phone” parameter or 
using “Tel:” in SIP packets, if the base has an assigned PSTN Number.  
•  Disabled: Will use “SIP User ID” information in the Request-Line and “From” 
header. 
•  User=Phone: “User=Phone” parameter will be attached to the Request-Line 
and “From” header in the SIP request to indicate the E.164 number. If set to 
"Enable". 
•  Enabled: "Tel:" will be used instead of "sip:" in the SIP request. 
Please consult your carrier before changing this parameter. Default is Disabled. 
Do Not Escape ‘#’ 
as %23 in SIP URI 
Replaces “#” by “%23” when sending SIP packets. Default is No. 
Disable Multiple m 
Line in SDP 
Sends only one m line in SDP, regardless of how many m fields are in the incoming 
SDP. Default is No. 










